1391262640 has 80 divisors (see below), whose sum is σ = 3484348416. Its totient is φ = 515116800.

The previous prime is 1391262611. The next prime is 1391262647. The reversal of 1391262640 is 462621931.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×1391262640² = 3871223466919539200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1391262596 and 1391262605.

It is not an unprimeable number, because it can be changed into a prime (1391262647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44845 + ... + 69235.

Almost surely, 2^1391262640 is an apocalyptic number.

1391262640 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 1391262640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1742174208).

1391262640 is an abundant number, since it is smaller than the sum of its proper divisors (2093085776).

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

1391262640 is a wasteful number, since it uses less digits than its factorization.

1391262640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24458 (or 24452 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 34.

The square root of 1391262640 is about 37299.6332421647. The cubic root of 1391262640 is about 1116.3568485805.

The spelling of 1391262640 in words is "one billion, three hundred ninety-one million, two hundred sixty-two thousand, six hundred forty".