21542375 has 32 divisors (see below), whose sum is σ = 28753920. Its totient is φ = 16077600.

The previous prime is 21542363. The next prime is 21542377. The reversal of 21542375 is 57324512.

It is a happy number.

It is not a de Polignac number, because 21542375 - 2⁸ = 21542119 is a prime.

It is a super-4 number, since 4×21542375⁴ (a number of 30 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542377) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 169562 + ... + 169688.

It is an arithmetic number, because the mean of its divisors is an integer number (898560).

Almost surely, 2^21542375 is an apocalyptic number.

21542375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21542375 is a deficient number, since it is larger than the sum of its proper divisors (7211545).

21542375 is a wasteful number, since it uses less digits than its factorization.

21542375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224 (or 214 counting only the distinct ones).

The product of its digits is 8400, while the sum is 29.

The square root of 21542375 is about 4641.3764122295. The cubic root of 21542375 is about 278.2474506044.

Adding to 21542375 its reverse (57324512), we get a palindrome (78866887).

The spelling of 21542375 in words is "twenty-one million, five hundred forty-two thousand, three hundred seventy-five".