51564156521 has 2 divisors, whose sum is σ = 51564156522. Its totient is φ = 51564156520.

The previous prime is 51564156493. The next prime is 51564156541. The reversal of 51564156521 is 12565146515.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 48514908121 + 3049248400 = 220261^2 + 55220^2 .

It is a cyclic number.

It is not a de Polignac number, because 51564156521 - 2¹⁴ = 51564140137 is a prime.

It is not a weakly prime, because it can be changed into another prime (51564156541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25782078260 + 25782078261.

It is an arithmetic number, because the mean of its divisors is an integer number (25782078261).

Almost surely, 2^51564156521 is an apocalyptic number.

It is an amenable number.

51564156521 is a deficient number, since it is larger than the sum of its proper divisors (1).

51564156521 is an equidigital number, since it uses as much as digits as its factorization.

51564156521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 180000, while the sum is 41.

The spelling of 51564156521 in words is "fifty-one billion, five hundred sixty-four million, one hundred fifty-six thousand, five hundred twenty-one".