21085157493 has 8 divisors (see below), whose sum is σ = 31237270400. Its totient is φ = 14056771644.

The previous prime is 21085157461. The next prime is 21085157497. The reversal of 21085157493 is 39475158012.

21085157493 is a `hidden beast` number, since 2 + 1 + 0 + 8 + 5 + 157 + 493 = 666.

It is not a de Polignac number, because 21085157493 - 2⁵ = 21085157461 is a prime.

It is a super-2 number, since 2×21085157493² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21085157497) 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 in 7 ways as a sum of consecutive naturals, for example, 390465853 + ... + 390465906.

It is an arithmetic number, because the mean of its divisors is an integer number (3904658800).

Almost surely, 2^21085157493 is an apocalyptic number.

It is an amenable number.

21085157493 is a deficient number, since it is larger than the sum of its proper divisors (10152112907).

21085157493 is an equidigital number, since it uses as much as digits as its factorization.

21085157493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 780931768 (or 780931762 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The spelling of 21085157493 in words is "twenty-one billion, eighty-five million, one hundred fifty-seven thousand, four hundred ninety-three".