21157610249 has 2 divisors, whose sum is σ = 21157610250. Its totient is φ = 21157610248.

The previous prime is 21157610171. The next prime is 21157610251. The reversal of 21157610249 is 94201675112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20211740224 + 945870025 = 142168^2 + 30755^2 .

It is a cyclic number.

It is not a de Polignac number, because 21157610249 - 2¹² = 21157606153 is a prime.

Together with 21157610251, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21157615249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578805124 + 10578805125.

It is an arithmetic number, because the mean of its divisors is an integer number (10578805125).

Almost surely, 2^21157610249 is an apocalyptic number.

It is an amenable number.

21157610249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21157610249 is an equidigital number, since it uses as much as digits as its factorization.

21157610249 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 21157610249 in words is "twenty-one billion, one hundred fifty-seven million, six hundred ten thousand, two hundred forty-nine".