1397531637 has 28 divisors (see below), whose sum is σ = 2124123084. Its totient is φ = 918889920.

The previous prime is 1397531633. The next prime is 1397531659. The reversal of 1397531637 is 7361357931.

1397531637 is a `hidden beast` number, since 1 + 3 + 9 + 7 + 5 + 3 + 1 + 637 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 282038436 + 1115493201 = 16794^2 + 33399^2 .

It is not a de Polignac number, because 1397531637 - 2² = 1397531633 is a prime.

It is a Smith number, since the sum of its digits (45) 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 = 1397531592 and 1397531601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1397531633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 40087 + ... + 66347.

Almost surely, 2^1397531637 is an apocalyptic number.

It is an amenable number.

1397531637 is a deficient number, since it is larger than the sum of its proper divisors (726591447).

1397531637 is an frugal number, since it uses more digits than its factorization.

1397531637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26352 (or 26337 counting only the distinct ones).

The product of its digits is 357210, while the sum is 45.

The square root of 1397531637 is about 37383.5744278152. The cubic root of 1397531637 is about 1118.0310956924.

The spelling of 1397531637 in words is "one billion, three hundred ninety-seven million, five hundred thirty-one thousand, six hundred thirty-seven".