21941663957 has 2 divisors, whose sum is σ = 21941663958. Its totient is φ = 21941663956.

The previous prime is 21941663917. The next prime is 21941663963. The reversal of 21941663957 is 75936614912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21939830641 + 1833316 = 148121^2 + 1354^2 .

It is a cyclic number.

It is not a de Polignac number, because 21941663957 - 2¹⁶ = 21941598421 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21941663899 and 21941663908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21941663917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10970831978 + 10970831979.

It is an arithmetic number, because the mean of its divisors is an integer number (10970831979).

Almost surely, 2^21941663957 is an apocalyptic number.

It is an amenable number.

21941663957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21941663957 is an equidigital number, since it uses as much as digits as its factorization.

21941663957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2449440, while the sum is 53.

The spelling of 21941663957 in words is "twenty-one billion, nine hundred forty-one million, six hundred sixty-three thousand, nine hundred fifty-seven".