21275507 has 4 divisors (see below), whose sum is σ = 23209656. Its totient is φ = 19341360.

The previous prime is 21275503. The next prime is 21275509. The reversal of 21275507 is 70557212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21275507 - 2² = 21275503 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21275507.

It is not an unprimeable number, because it can be changed into a prime (21275503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 967058 + ... + 967079.

It is an arithmetic number, because the mean of its divisors is an integer number (5802414).

Almost surely, 2^21275507 is an apocalyptic number.

21275507 is a deficient number, since it is larger than the sum of its proper divisors (1934149).

21275507 is a wasteful number, since it uses less digits than its factorization.

21275507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1934148.

The product of its (nonzero) digits is 4900, while the sum is 29.

The square root of 21275507 is about 4612.5380215235. The cubic root of 21275507 is about 277.0936921046.

The spelling of 21275507 in words is "twenty-one million, two hundred seventy-five thousand, five hundred seven".