21675531 has 4 divisors (see below), whose sum is σ = 28900712. Its totient is φ = 14450352.

The previous prime is 21675529. The next prime is 21675553. The reversal of 21675531 is 13557612.

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

It is not a de Polignac number, because 21675531 - 2¹ = 21675529 is a prime.

It is a super-2 number, since 2×21675531² = 939657288263922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21675571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3612586 + ... + 3612591.

It is an arithmetic number, because the mean of its divisors is an integer number (7225178).

Almost surely, 2^21675531 is an apocalyptic number.

21675531 is a deficient number, since it is larger than the sum of its proper divisors (7225181).

21675531 is an equidigital number, since it uses as much as digits as its factorization.

21675531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7225180.

The product of its digits is 6300, while the sum is 30.

The square root of 21675531 is about 4655.6987660286. The cubic root of 21675531 is about 278.8195670510.

The spelling of 21675531 in words is "twenty-one million, six hundred seventy-five thousand, five hundred thirty-one".