21640627 has 4 divisors (see below), whose sum is σ = 21651480. Its totient is φ = 21629776.

The previous prime is 21640621. The next prime is 21640637. The reversal of 21640627 is 72604612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21640627 - 2⁷ = 21640499 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21640595 and 21640604.

It is not an unprimeable number, because it can be changed into a prime (21640621) 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, 1477 + ... + 6742.

It is an arithmetic number, because the mean of its divisors is an integer number (5412870).

Almost surely, 2^21640627 is an apocalyptic number.

21640627 is a deficient number, since it is larger than the sum of its proper divisors (10853).

21640627 is an equidigital number, since it uses as much as digits as its factorization.

21640627 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10852.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21640627 is about 4651.9487314458. The cubic root of 21640627 is about 278.6698260582.

The spelling of 21640627 in words is "twenty-one million, six hundred forty thousand, six hundred twenty-seven".