21257275 has 12 divisors (see below), whose sum is σ = 28387072. Its totient is φ = 15697440.

The previous prime is 21257273. The next prime is 21257279. The reversal of 21257275 is 57275212.

It is not a de Polignac number, because 21257275 - 2¹ = 21257273 is a prime.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21257273) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32379 + ... + 33028.

Almost surely, 2^21257275 is an apocalyptic number.

21257275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21257275 is a deficient number, since it is larger than the sum of its proper divisors (7129797).

21257275 is a wasteful number, since it uses less digits than its factorization.

21257275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65430 (or 65425 counting only the distinct ones).

The product of its digits is 9800, while the sum is 31.

The square root of 21257275 is about 4610.5612456620. The cubic root of 21257275 is about 277.0145178696.

The spelling of 21257275 in words is "twenty-one million, two hundred fifty-seven thousand, two hundred seventy-five".