21085157497 has 2 divisors, whose sum is σ = 21085157498. Its totient is φ = 21085157496.

The previous prime is 21085157461. The next prime is 21085157537. The reversal of 21085157497 is 79475158012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17050875241 + 4034282256 = 130579^2 + 63516^2 .

It is a cyclic number.

It is not a de Polignac number, because 21085157497 - 2¹⁵ = 21085124729 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21085157497.

It is not a weakly prime, because it can be changed into another prime (21085157407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542578748 + 10542578749.

It is an arithmetic number, because the mean of its divisors is an integer number (10542578749).

Almost surely, 2^21085157497 is an apocalyptic number.

It is an amenable number.

21085157497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21085157497 is an equidigital number, since it uses as much as digits as its factorization.

21085157497 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 705600, while the sum is 49.

The spelling of 21085157497 in words is "twenty-one billion, eighty-five million, one hundred fifty-seven thousand, four hundred ninety-seven".