21487275 has 54 divisors (see below), whose sum is σ = 40269372. Its totient is φ = 11372400.

The previous prime is 21487273. The next prime is 21487283. The reversal of 21487275 is 57278412.

It is not a de Polignac number, because 21487275 - 2¹ = 21487273 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21487273) by changing a digit.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 163960 + ... + 164090.

Almost surely, 2^21487275 is an apocalyptic number.

21487275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21487275 is a deficient number, since it is larger than the sum of its proper divisors (18782097).

21487275 is an frugal number, since it uses more digits than its factorization.

21487275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165 (or 139 counting only the distinct ones).

The product of its digits is 31360, while the sum is 36.

The square root of 21487275 is about 4635.4368726151. The cubic root of 21487275 is about 278.0100189616.

The spelling of 21487275 in words is "twenty-one million, four hundred eighty-seven thousand, two hundred seventy-five".