21590747 has 4 divisors (see below), whose sum is σ = 21671280. Its totient is φ = 21510216.

The previous prime is 21590741. The next prime is 21590749. The reversal of 21590747 is 74709512.

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 21590747 - 2¹⁸ = 21328603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21590741) 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, 39863 + ... + 40400.

It is an arithmetic number, because the mean of its divisors is an integer number (5417820).

Almost surely, 2^21590747 is an apocalyptic number.

21590747 is a deficient number, since it is larger than the sum of its proper divisors (80533).

21590747 is an equidigital number, since it uses as much as digits as its factorization.

21590747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80532.

The product of its (nonzero) digits is 17640, while the sum is 35.

The square root of 21590747 is about 4646.5844445141. The cubic root of 21590747 is about 278.4555570948.

The spelling of 21590747 in words is "twenty-one million, five hundred ninety thousand, seven hundred forty-seven".