1387256640 has 448 divisors, whose sum is σ = 5618073600. Its totient is φ = 287508480.

The previous prime is 1387256621. The next prime is 1387256659. The reversal of 1387256640 is 466527831.

1387256640 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (1387256621) and next prime (1387256659).

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 1387256592 and 1387256601.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3621889 + ... + 3622271.

Almost surely, 2^1387256640 is an apocalyptic number.

1387256640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1387256640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2809036800).

1387256640 is an abundant number, since it is smaller than the sum of its proper divisors (4230816960).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1387256640 is a wasteful number, since it uses less digits than its factorization.

1387256640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435 (or 411 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

The square root of 1387256640 is about 37245.8942703756. The cubic root of 1387256640 is about 1115.2843396642.

The spelling of 1387256640 in words is "one billion, three hundred eighty-seven million, two hundred fifty-six thousand, six hundred forty".