21613557 has 12 divisors (see below), whose sum is σ = 33523296. Its totient is φ = 12350520.

The previous prime is 21613517. The next prime is 21613577. The reversal of 21613557 is 75531612.

It is not a de Polignac number, because 21613557 - 2¹² = 21609461 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21613517) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 73369 + ... + 73662.

It is an arithmetic number, because the mean of its divisors is an integer number (2793608).

Almost surely, 2^21613557 is an apocalyptic number.

It is an amenable number.

21613557 is a deficient number, since it is larger than the sum of its proper divisors (11909739).

21613557 is a wasteful number, since it uses less digits than its factorization.

21613557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147048 (or 147041 counting only the distinct ones).

The product of its digits is 6300, while the sum is 30.

The square root of 21613557 is about 4649.0382876462. The cubic root of 21613557 is about 278.5535826644.

The spelling of 21613557 in words is "twenty-one million, six hundred thirteen thousand, five hundred fifty-seven".