1387205840 has 20 divisors (see below), whose sum is σ = 3225253764. Its totient is φ = 554882304.

The previous prime is 1387205839. The next prime is 1387205851. The reversal of 1387205840 is 485027831.

It can be written as a sum of positive squares in 2 ways, for example, as 654745744 + 732460096 = 25588^2 + 27064^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 1387205794 and 1387205803.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8669957 + ... + 8670116.

Almost surely, 2^1387205840 is an apocalyptic number.

1387205840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1387205840 is an abundant number, since it is smaller than the sum of its proper divisors (1838047924).

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

1387205840 is a wasteful number, since it uses less digits than its factorization.

1387205840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17340086 (or 17340080 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 38.

The square root of 1387205840 is about 37245.2123097721. The cubic root of 1387205840 is about 1115.2707259524.

The spelling of 1387205840 in words is "one billion, three hundred eighty-seven million, two hundred five thousand, eight hundred forty".