21552819 has 4 divisors (see below), whose sum is σ = 28737096. Its totient is φ = 14368544.

The previous prime is 21552799. The next prime is 21552823. The reversal of 21552819 is 91825512.

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 21552819 - 2⁷ = 21552691 is a prime.

It is a super-2 number, since 2×21552819² = 929048013693522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21552819.

It is not an unprimeable number, because it can be changed into a prime (21552119) 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, 3592134 + ... + 3592139.

It is an arithmetic number, because the mean of its divisors is an integer number (7184274).

Almost surely, 2^21552819 is an apocalyptic number.

21552819 is a deficient number, since it is larger than the sum of its proper divisors (7184277).

21552819 is an equidigital number, since it uses as much as digits as its factorization.

21552819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7184276.

The product of its digits is 7200, while the sum is 33.

The square root of 21552819 is about 4642.5013731823. The cubic root of 21552819 is about 278.2924092325.

The spelling of 21552819 in words is "twenty-one million, five hundred fifty-two thousand, eight hundred nineteen".