51531681 has 8 divisors (see below), whose sum is σ = 68914144. Its totient is φ = 34251840.

The previous prime is 51531679. The next prime is 51531731. The reversal of 51531681 is 18613515.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51531681 - 2¹ = 51531679 is a prime.

It is a super-2 number, since 2×51531681² = 5311028293371522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51531631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24475 + ... + 26496.

It is an arithmetic number, because the mean of its divisors is an integer number (8614268).

Almost surely, 2^51531681 is an apocalyptic number.

It is an amenable number.

51531681 is a deficient number, since it is larger than the sum of its proper divisors (17382463).

51531681 is a wasteful number, since it uses less digits than its factorization.

51531681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51311.

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

The square root of 51531681 is about 7178.5570277041. The cubic root of 51531681 is about 372.1272183105.

The spelling of 51531681 in words is "fifty-one million, five hundred thirty-one thousand, six hundred eighty-one".