51515001021 has 16 divisors (see below), whose sum is σ = 75018385728. Its totient is φ = 31184764800.

The previous prime is 51515001007. The next prime is 51515001047. The reversal of 51515001021 is 12010051515.

It is not a de Polignac number, because 51515001021 - 2⁷ = 51515000893 is a prime.

It is a super-3 number, since 3×51515001021³ (a number of 33 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51515001221) 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, 882490 + ... + 939051.

It is an arithmetic number, because the mean of its divisors is an integer number (4688649108).

Almost surely, 2^51515001021 is an apocalyptic number.

It is an amenable number.

51515001021 is a deficient number, since it is larger than the sum of its proper divisors (23503384707).

51515001021 is a wasteful number, since it uses less digits than its factorization.

51515001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1822412.

The product of its (nonzero) digits is 250, while the sum is 21.

Adding to 51515001021 its reverse (12010051515), we get a palindrome (63525052536).

The spelling of 51515001021 in words is "fifty-one billion, five hundred fifteen million, one thousand, twenty-one".