21613605 has 32 divisors (see below), whose sum is σ = 37470720. Its totient is φ = 10575360.

The previous prime is 21613591. The next prime is 21613609. The reversal of 21613605 is 50631612.

It is not a de Polignac number, because 21613605 - 2⁸ = 21613349 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21613609) 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 31 ways as a sum of consecutive naturals, for example, 52641 + ... + 53049.

It is an arithmetic number, because the mean of its divisors is an integer number (1170960).

Almost surely, 2^21613605 is an apocalyptic number.

It is an amenable number.

21613605 is a deficient number, since it is larger than the sum of its proper divisors (15857115).

21613605 is a wasteful number, since it uses less digits than its factorization.

21613605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 701.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21613605 is about 4649.0434500013. The cubic root of 21613605 is about 278.5537888708.

The spelling of 21613605 in words is "twenty-one million, six hundred thirteen thousand, six hundred five".