51178742221 has 2 divisors, whose sum is σ = 51178742222. Its totient is φ = 51178742220.

The previous prime is 51178742149. The next prime is 51178742257. The reversal of 51178742221 is 12224787115.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39501562500 + 11677179721 = 198750^2 + 108061^2 .

It is a cyclic number.

It is not a de Polignac number, because 51178742221 - 2²⁹ = 50641871309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51178745221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25589371110 + 25589371111.

It is an arithmetic number, because the mean of its divisors is an integer number (25589371111).

Almost surely, 2^51178742221 is an apocalyptic number.

It is an amenable number.

51178742221 is a deficient number, since it is larger than the sum of its proper divisors (1).

51178742221 is an equidigital number, since it uses as much as digits as its factorization.

51178742221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62720, while the sum is 40.

The spelling of 51178742221 in words is "fifty-one billion, one hundred seventy-eight million, seven hundred forty-two thousand, two hundred twenty-one".