51997581 has 6 divisors (see below), whose sum is σ = 75107630. Its totient is φ = 34665048.

The previous prime is 51997541. The next prime is 51997597. The reversal of 51997581 is 18579915.

It can be written as a sum of positive squares in only one way, i.e., 44756100 + 7241481 = 6690^2 + 2691^2 .

It is not a de Polignac number, because 51997581 - 2⁷ = 51997453 is a prime.

It is a super-2 number, since 2×51997581² = 5407496859703122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51997541) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2888746 + ... + 2888763.

Almost surely, 2^51997581 is an apocalyptic number.

It is an amenable number.

51997581 is a deficient number, since it is larger than the sum of its proper divisors (23110049).

51997581 is a wasteful number, since it uses less digits than its factorization.

51997581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5777515 (or 5777512 counting only the distinct ones).

The product of its digits is 113400, while the sum is 45.

The square root of 51997581 is about 7210.9348215055. The cubic root of 51997581 is about 373.2453278070.

The spelling of 51997581 in words is "fifty-one million, nine hundred ninety-seven thousand, five hundred eighty-one".