21099375 has 90 divisors (see below), whose sum is σ = 43211168. Its totient is φ = 9900000.

The previous prime is 21099371. The next prime is 21099383. The reversal of 21099375 is 57399012.

It is not a de Polignac number, because 21099375 - 2² = 21099371 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099371) by changing a digit.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 680610 + ... + 680640.

Almost surely, 2^21099375 is an apocalyptic number.

21099375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21099375 is an abundant number, since it is smaller than the sum of its proper divisors (22111793).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21099375 is a wasteful number, since it uses less digits than its factorization.

21099375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79 (or 50 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 21099375 is about 4593.4055993348. The cubic root of 21099375 is about 276.3269204252.

The spelling of 21099375 in words is "twenty-one million, ninety-nine thousand, three hundred seventy-five".