21575989 has 4 divisors (see below), whose sum is σ = 21585280. Its totient is φ = 21566700.

The previous prime is 21575987. The next prime is 21576011. The reversal of 21575989 is 98957512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, 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 21575989 - 2¹ = 21575987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21575987) 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, 2314 + ... + 6964.

It is an arithmetic number, because the mean of its divisors is an integer number (5396320).

Almost surely, 2^21575989 is an apocalyptic number.

It is an amenable number.

21575989 is a deficient number, since it is larger than the sum of its proper divisors (9291).

21575989 is an equidigital number, since it uses as much as digits as its factorization.

21575989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9290.

The product of its digits is 226800, while the sum is 46.

The square root of 21575989 is about 4644.9961248638. The cubic root of 21575989 is about 278.3920980618.

The spelling of 21575989 in words is "twenty-one million, five hundred seventy-five thousand, nine hundred eighty-nine".