21554879 has 4 divisors (see below), whose sum is σ = 21610680. Its totient is φ = 21499080.

The previous prime is 21554849. The next prime is 21554881. The reversal of 21554879 is 97845512.

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 21554879 - 2²⁰ = 20506303 is a prime.

It is a super-2 number, since 2×21554879² = 929225617409282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554809) 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, 27317 + ... + 28094.

It is an arithmetic number, because the mean of its divisors is an integer number (5402670).

Almost surely, 2^21554879 is an apocalyptic number.

21554879 is a deficient number, since it is larger than the sum of its proper divisors (55801).

21554879 is an equidigital number, since it uses as much as digits as its factorization.

21554879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55800.

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

The square root of 21554879 is about 4642.7232310359. The cubic root of 21554879 is about 278.3012752668.

The spelling of 21554879 in words is "twenty-one million, five hundred fifty-four thousand, eight hundred seventy-nine".