51531021 has 24 divisors (see below), whose sum is σ = 80887040. Its totient is φ = 31492800.

The previous prime is 51531001. The next prime is 51531049. The reversal of 51531021 is 12013515.

It is not a de Polignac number, because 51531021 - 2¹⁴ = 51514637 is a prime.

It is a super-2 number, since 2×51531021² = 5310892250604882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51530985 and 51531003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51531001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 441 + ... + 10161.

Almost surely, 2^51531021 is an apocalyptic number.

It is an amenable number.

51531021 is a deficient number, since it is larger than the sum of its proper divisors (29356019).

51531021 is a wasteful number, since it uses less digits than its factorization.

51531021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9777 (or 9774 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 51531021 is about 7178.5110573154. The cubic root of 51531021 is about 372.1256296114.

Adding to 51531021 its reverse (12013515), we get a palindrome (63544536).

The spelling of 51531021 in words is "fifty-one million, five hundred thirty-one thousand, twenty-one".