21157583697493 has 2 divisors, whose sum is σ = 21157583697494. Its totient is φ = 21157583697492.

The previous prime is 21157583697479. The next prime is 21157583697499. The reversal of 21157583697493 is 39479638575112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11488425533764 + 9669158163729 = 3389458^2 + 3109527^2 .

It is a cyclic number.

It is not a de Polignac number, because 21157583697493 - 2⁵ = 21157583697461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21157583697499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578791848746 + 10578791848747.

It is an arithmetic number, because the mean of its divisors is an integer number (10578791848747).

Almost surely, 2^{21157583697493} is an apocalyptic number.

It is an amenable number.

21157583697493 is a deficient number, since it is larger than the sum of its proper divisors (1).

21157583697493 is an equidigital number, since it uses as much as digits as its factorization.

21157583697493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 342921600, while the sum is 70.

The spelling of 21157583697493 in words is "twenty-one trillion, one hundred fifty-seven billion, five hundred eighty-three million, six hundred ninety-seven thousand, four hundred ninety-three".