21557193 has 16 divisors (see below), whose sum is σ = 32919936. Its totient is φ = 12291840.

The previous prime is 21557177. The next prime is 21557197. The reversal of 21557193 is 39175512.

It is not a de Polignac number, because 21557193 - 2⁴ = 21557177 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21557197) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13105 + ... + 14657.

It is an arithmetic number, because the mean of its divisors is an integer number (2057496).

Almost surely, 2^21557193 is an apocalyptic number.

It is an amenable number.

21557193 is a deficient number, since it is larger than the sum of its proper divisors (11362743).

21557193 is a wasteful number, since it uses less digits than its factorization.

21557193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2224.

The product of its digits is 9450, while the sum is 33.

The square root of 21557193 is about 4642.9724315356. The cubic root of 21557193 is about 278.3112338181.

The spelling of 21557193 in words is "twenty-one million, five hundred fifty-seven thousand, one hundred ninety-three".