21156179453 has 2 divisors, whose sum is σ = 21156179454. Its totient is φ = 21156179452.

The previous prime is 21156179449. The next prime is 21156179477. The reversal of 21156179453 is 35497165112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20546928964 + 609250489 = 143342^2 + 24683^2 .

It is a cyclic number.

It is not a de Polignac number, because 21156179453 - 2² = 21156179449 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21156139453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578089726 + 10578089727.

It is an arithmetic number, because the mean of its divisors is an integer number (10578089727).

Almost surely, 2^21156179453 is an apocalyptic number.

It is an amenable number.

21156179453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21156179453 is an equidigital number, since it uses as much as digits as its factorization.

21156179453 is an evil number, because the sum of its binary digits is even.

The product of its digits is 226800, while the sum is 44.

The spelling of 21156179453 in words is "twenty-one billion, one hundred fifty-six million, one hundred seventy-nine thousand, four hundred fifty-three".