21553339 has 4 divisors (see below), whose sum is σ = 22248640. Its totient is φ = 20858040.

The previous prime is 21553319. The next prime is 21553361. The reversal of 21553339 is 93335512.

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

It is a de Polignac number, because none of the positive numbers 2^k-21553339 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 695269 = 21553339 / (2 + 1 + 5 + 5 + 3 + 3 + 3 + 9).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21553339.

It is not an unprimeable number, because it can be changed into a prime (21553309) 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, 347604 + ... + 347665.

It is an arithmetic number, because the mean of its divisors is an integer number (5562160).

Almost surely, 2^21553339 is an apocalyptic number.

21553339 is a deficient number, since it is larger than the sum of its proper divisors (695301).

21553339 is an equidigital number, since it uses as much as digits as its factorization.

21553339 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695300.

The product of its digits is 12150, while the sum is 31.

The square root of 21553339 is about 4642.5573771360. The cubic root of 21553339 is about 278.2946473138.

The spelling of 21553339 in words is "twenty-one million, five hundred fifty-three thousand, three hundred thirty-nine".