21554579 has 4 divisors (see below), whose sum is σ = 22249920. Its totient is φ = 20859240.

The previous prime is 21554573. The next prime is 21554581. The reversal of 21554579 is 97545512.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21554579 - 2²⁴ = 4777363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21554573) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 347624 + ... + 347685.

It is an arithmetic number, because the mean of its divisors is an integer number (5562480).

Almost surely, 2^21554579 is an apocalyptic number.

21554579 is a deficient number, since it is larger than the sum of its proper divisors (695341).

21554579 is an equidigital number, since it uses as much as digits as its factorization.

21554579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695340.

The product of its digits is 63000, while the sum is 38.

The square root of 21554579 is about 4642.6909222993. The cubic root of 21554579 is about 278.2999841319.

The spelling of 21554579 in words is "twenty-one million, five hundred fifty-four thousand, five hundred seventy-nine".