21557422 has 4 divisors (see below), whose sum is σ = 32336136. Its totient is φ = 10778710.

The previous prime is 21557407. The next prime is 21557447. The reversal of 21557422 is 22475512.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5389354 + ... + 5389357.

It is an arithmetic number, because the mean of its divisors is an integer number (8084034).

Almost surely, 2^21557422 is an apocalyptic number.

21557422 is a deficient number, since it is larger than the sum of its proper divisors (10778714).

21557422 is a wasteful number, since it uses less digits than its factorization.

21557422 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10778713.

The product of its digits is 5600, while the sum is 28.

The square root of 21557422 is about 4642.9970923962. The cubic root of 21557422 is about 278.3122193058.

The spelling of 21557422 in words is "twenty-one million, five hundred fifty-seven thousand, four hundred twenty-two".