21019998953 has 2 divisors, whose sum is σ = 21019998954. Its totient is φ = 21019998952.

The previous prime is 21019998887. The next prime is 21019999001. The reversal of 21019998953 is 35989991012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19980387904 + 1039611049 = 141352^2 + 32243^2 .

It is a cyclic number.

It is not a de Polignac number, because 21019998953 - 2³² = 16725031657 is a prime.

It is not a weakly prime, because it can be changed into another prime (21019988953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509999476 + 10509999477.

It is an arithmetic number, because the mean of its divisors is an integer number (10509999477).

Almost surely, 2^21019998953 is an apocalyptic number.

It is an amenable number.

21019998953 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019998953 is an equidigital number, since it uses as much as digits as its factorization.

21019998953 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1574640, while the sum is 56.

The spelling of 21019998953 in words is "twenty-one billion, nineteen million, nine hundred ninety-eight thousand, nine hundred fifty-three".