51631581 has 16 divisors (see below), whose sum is σ = 69713280. Its totient is φ = 33988800.

The previous prime is 51631579. The next prime is 51631589. The reversal of 51631581 is 18513615.

It is not a de Polignac number, because 51631581 - 2¹ = 51631579 is a prime.

It is a super-2 number, since 2×51631581² = 5331640313119122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51631589) 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, 132535 + ... + 132923.

It is an arithmetic number, because the mean of its divisors is an integer number (4357080).

Almost surely, 2^51631581 is an apocalyptic number.

It is an amenable number.

51631581 is a deficient number, since it is larger than the sum of its proper divisors (18081699).

51631581 is a wasteful number, since it uses less digits than its factorization.

51631581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 836.

The product of its digits is 3600, while the sum is 30.

The square root of 51631581 is about 7185.5118815572. The cubic root of 51631581 is about 372.3675333377.

The spelling of 51631581 in words is "fifty-one million, six hundred thirty-one thousand, five hundred eighty-one".