21554279 has 4 divisors (see below), whose sum is σ = 22297560. Its totient is φ = 20811000.

The previous prime is 21554257. The next prime is 21554297. The reversal of 21554279 is 97245512.

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 21554279 - 2¹² = 21550183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554209) 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, 371597 + ... + 371654.

It is an arithmetic number, because the mean of its divisors is an integer number (5574390).

Almost surely, 2^21554279 is an apocalyptic number.

21554279 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21554279 is a deficient number, since it is larger than the sum of its proper divisors (743281).

21554279 is an equidigital number, since it uses as much as digits as its factorization.

21554279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743280.

The product of its digits is 25200, while the sum is 35.

The square root of 21554279 is about 4642.6586133378. The cubic root of 21554279 is about 278.2986929850.

The spelling of 21554279 in words is "twenty-one million, five hundred fifty-four thousand, two hundred seventy-nine".