21557894 has 16 divisors (see below), whose sum is σ = 34148400. Its totient is φ = 10178784.

The previous prime is 21557843. The next prime is 21557917. The reversal of 21557894 is 49875512.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 14372 + ... + 15800.

It is an arithmetic number, because the mean of its divisors is an integer number (2134275).

Almost surely, 2^21557894 is an apocalyptic number.

21557894 is a deficient number, since it is larger than the sum of its proper divisors (12590506).

21557894 is a wasteful number, since it uses less digits than its factorization.

21557894 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1847.

The product of its digits is 100800, while the sum is 41.

The square root of 21557894 is about 4643.0479213551. The cubic root of 21557894 is about 278.3142505074.

The spelling of 21557894 in words is "twenty-one million, five hundred fifty-seven thousand, eight hundred ninety-four".