51515515021 has 8 divisors (see below), whose sum is σ = 54565731000. Its totient is φ = 48467509248.

The previous prime is 51515515003. The next prime is 51515515027. The reversal of 51515515021 is 12051551515.

It is a happy number.

51515515021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 20103269796 + 31412245225 = 141786^2 + 177235^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 51515515021 - 2⁹ = 51515514509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51515515027) 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, 504436 + ... + 597901.

It is an arithmetic number, because the mean of its divisors is an integer number (6820716375).

Almost surely, 2^51515515021 is an apocalyptic number.

It is an amenable number.

51515515021 is a deficient number, since it is larger than the sum of its proper divisors (3050215979).

51515515021 is a wasteful number, since it uses less digits than its factorization.

51515515021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1105103.

The product of its (nonzero) digits is 6250, while the sum is 31.

The spelling of 51515515021 in words is "fifty-one billion, five hundred fifteen million, five hundred fifteen thousand, twenty-one".