51521010021 has 12 divisors (see below), whose sum is σ = 80143793548. Its totient is φ = 31705236864.

The previous prime is 51521010011. The next prime is 51521010049. The reversal of 51521010021 is 12001012515.

It can be written as a sum of positive squares in 2 ways, for example, as 31342807521 + 20178202500 = 177039^2 + 142050^2 .

It is not a de Polignac number, because 51521010021 - 2¹⁰ = 51521008997 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51521009976 and 51521010003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51521010011) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 220175140 + ... + 220175373.

Almost surely, 2^51521010021 is an apocalyptic number.

It is an amenable number.

51521010021 is a deficient number, since it is larger than the sum of its proper divisors (28622783527).

51521010021 is a wasteful number, since it uses less digits than its factorization.

51521010021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440350532 (or 440350529 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 18.

Adding to 51521010021 its reverse (12001012515), we get a palindrome (63522022536).

The spelling of 51521010021 in words is "fifty-one billion, five hundred twenty-one million, ten thousand, twenty-one".