21540375 has 48 divisors (see below), whose sum is σ = 39862368. Its totient is φ = 11184000.

The previous prime is 21540367. The next prime is 21540383. The reversal of 21540375 is 57304512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21540367) and next prime (21540383).

It is not a de Polignac number, because 21540375 - 2³ = 21540367 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 45892 + ... + 46358.

It is an arithmetic number, because the mean of its divisors is an integer number (830466).

Almost surely, 2^21540375 is an apocalyptic number.

21540375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21540375 is a deficient number, since it is larger than the sum of its proper divisors (18321993).

21540375 is a wasteful number, since it uses less digits than its factorization.

21540375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 529 (or 516 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 27.

The square root of 21540375 is about 4641.1609538994. The cubic root of 21540375 is about 278.2388394814.

Adding to 21540375 its reverse (57304512), we get a palindrome (78844887).

The spelling of 21540375 in words is "twenty-one million, five hundred forty thousand, three hundred seventy-five".