21100978253 has 2 divisors, whose sum is σ = 21100978254. Its totient is φ = 21100978252.

The previous prime is 21100978229. The next prime is 21100978271. The reversal of 21100978253 is 35287900112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19954952644 + 1146025609 = 141262^2 + 33853^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100978253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100978453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550489126 + 10550489127.

It is an arithmetic number, because the mean of its divisors is an integer number (10550489127).

Almost surely, 2^21100978253 is an apocalyptic number.

It is an amenable number.

21100978253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100978253 is an equidigital number, since it uses as much as digits as its factorization.

21100978253 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30240, while the sum is 38.

The spelling of 21100978253 in words is "twenty-one billion, one hundred million, nine hundred seventy-eight thousand, two hundred fifty-three".