12639999961 has 2 divisors, whose sum is σ = 12639999962. Its totient is φ = 12639999960.

The previous prime is 12639999947. The next prime is 12639999971. The reversal of 12639999961 is 16999993621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12623646025 + 16353936 = 112355^2 + 4044^2 .

It is a cyclic number.

It is not a de Polignac number, because 12639999961 - 2¹³ = 12639991769 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 12639999893 and 12639999902.

It is not a weakly prime, because it can be changed into another prime (12639999971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6319999980 + 6319999981.

It is an arithmetic number, because the mean of its divisors is an integer number (6319999981).

Almost surely, 2^12639999961 is an apocalyptic number.

It is an amenable number.

12639999961 is a deficient number, since it is larger than the sum of its proper divisors (1).

12639999961 is an equidigital number, since it uses as much as digits as its factorization.

12639999961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12754584, while the sum is 64.

The spelling of 12639999961 in words is "twelve billion, six hundred thirty-nine million, nine hundred ninety-nine thousand, nine hundred sixty-one".