21985818625 has 16 divisors (see below), whose sum is σ = 28022102784. Its totient is φ = 17214423600.

The previous prime is 21985818619. The next prime is 21985818637. The reversal of 21985818625 is 52681858912.

It is not a de Polignac number, because 21985818625 - 2¹¹ = 21985816577 is a prime.

It is a super-2 number, since 2×21985818625² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1865259 + ... + 1877008.

It is an arithmetic number, because the mean of its divisors is an integer number (1751381424).

Almost surely, 2^21985818625 is an apocalyptic number.

21985818625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21985818625 is a deficient number, since it is larger than the sum of its proper divisors (6036284159).

21985818625 is an equidigital number, since it uses as much as digits as its factorization.

21985818625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3742329 (or 3742319 counting only the distinct ones).

The product of its digits is 2764800, while the sum is 55.

The spelling of 21985818625 in words is "twenty-one billion, nine hundred eighty-five million, eight hundred eighteen thousand, six hundred twenty-five".