21580913 has 4 divisors (see below), whose sum is σ = 21841008. Its totient is φ = 21320820.

The previous prime is 21580907. The next prime is 21580919. The reversal of 21580913 is 31908512.

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.

It is an interprime number because it is at equal distance from previous prime (21580907) and next prime (21580919).

It is a cyclic number.

It is not a de Polignac number, because 21580913 - 2¹² = 21576817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21580919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 129923 + ... + 130088.

It is an arithmetic number, because the mean of its divisors is an integer number (5460252).

Almost surely, 2^21580913 is an apocalyptic number.

It is an amenable number.

21580913 is a deficient number, since it is larger than the sum of its proper divisors (260095).

21580913 is an equidigital number, since it uses as much as digits as its factorization.

21580913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260094.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 21580913 is about 4645.5261273617. The cubic root of 21580913 is about 278.4132743552.

The spelling of 21580913 in words is "twenty-one million, five hundred eighty thousand, nine hundred thirteen".