51570021621 has 4 divisors (see below), whose sum is σ = 68760028832. Its totient is φ = 34380014412.

The previous prime is 51570021599. The next prime is 51570021637. The reversal of 51570021621 is 12612007515.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 51570021621 - 2⁵ = 51570021589 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 (51570021121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8595003601 + ... + 8595003606.

It is an arithmetic number, because the mean of its divisors is an integer number (17190007208).

Almost surely, 2^51570021621 is an apocalyptic number.

It is an amenable number.

51570021621 is a deficient number, since it is larger than the sum of its proper divisors (17190007211).

51570021621 is a wasteful number, since it uses less digits than its factorization.

51570021621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17190007210.

The product of its (nonzero) digits is 4200, while the sum is 30.

The spelling of 51570021621 in words is "fifty-one billion, five hundred seventy million, twenty-one thousand, six hundred twenty-one".