51639961 has 2 divisors, whose sum is σ = 51639962. Its totient is φ = 51639960.

The previous prime is 51639919. The next prime is 51639971. The reversal of 51639961 is 16993615.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 34292736 + 17347225 = 5856^2 + 4165^2 .

It is a cyclic number.

It is not a de Polignac number, because 51639961 - 2⁹ = 51639449 is a prime.

It is not a weakly prime, because it can be changed into another prime (51639911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25819980 + 25819981.

It is an arithmetic number, because the mean of its divisors is an integer number (25819981).

Almost surely, 2^51639961 is an apocalyptic number.

It is an amenable number.

51639961 is a deficient number, since it is larger than the sum of its proper divisors (1).

51639961 is an equidigital number, since it uses as much as digits as its factorization.

51639961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43740, while the sum is 40.

The square root of 51639961 is about 7186.0949757153. The cubic root of 51639961 is about 372.3876777988.

The spelling of 51639961 in words is "fifty-one million, six hundred thirty-nine thousand, nine hundred sixty-one".