21106638375 has 16 divisors (see below), whose sum is σ = 35121446880. Its totient is φ = 11256873600.

The previous prime is 21106638361. The next prime is 21106638389. The reversal of 21106638375 is 57383660112.

It is an interprime number because it is at equal distance from previous prime (21106638361) and next prime (21106638389).

It is not a de Polignac number, because 21106638375 - 2¹³ = 21106630183 is a prime.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 28141810 + ... + 28142559.

It is an arithmetic number, because the mean of its divisors is an integer number (2195090430).

Almost surely, 2^21106638375 is an apocalyptic number.

21106638375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21106638375 is a deficient number, since it is larger than the sum of its proper divisors (14014808505).

21106638375 is an equidigital number, since it uses as much as digits as its factorization.

21106638375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56284387 (or 56284377 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 42.

The spelling of 21106638375 in words is "twenty-one billion, one hundred six million, six hundred thirty-eight thousand, three hundred seventy-five".