21375375 has 64 divisors (see below), whose sum is σ = 43130880. Its totient is φ = 9177600.

The previous prime is 21375373. The next prime is 21375379. The reversal of 21375375 is 57357312.

It is not a de Polignac number, because 21375375 - 2¹ = 21375373 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21375371) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 44386 + ... + 44864.

It is an arithmetic number, because the mean of its divisors is an integer number (673920).

Almost surely, 2^21375375 is an apocalyptic number.

21375375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21375375 is an abundant number, since it is smaller than the sum of its proper divisors (21755505).

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

21375375 is a wasteful number, since it uses less digits than its factorization.

21375375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521 (or 511 counting only the distinct ones).

The product of its digits is 22050, while the sum is 33.

The square root of 21375375 is about 4623.3510574041. The cubic root of 21375375 is about 277.5265780890.

The spelling of 21375375 in words is "twenty-one million, three hundred seventy-five thousand, three hundred seventy-five".