21010019957 has 2 divisors, whose sum is σ = 21010019958. Its totient is φ = 21010019956.

The previous prime is 21010019941. The next prime is 21010019969. The reversal of 21010019957 is 75991001012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15973420996 + 5036598961 = 126386^2 + 70969^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010019957 - 2⁴ = 21010019941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21010019917) 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, 10505009978 + 10505009979.

It is an arithmetic number, because the mean of its divisors is an integer number (10505009979).

Almost surely, 2^21010019957 is an apocalyptic number.

It is an amenable number.

21010019957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010019957 is an equidigital number, since it uses as much as digits as its factorization.

21010019957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5670, while the sum is 35.

The spelling of 21010019957 in words is "twenty-one billion, ten million, nineteen thousand, nine hundred fifty-seven".