21899855 has 4 divisors (see below), whose sum is σ = 26279832. Its totient is φ = 17519880.

The previous prime is 21899831. The next prime is 21899909. The reversal of 21899855 is 55899812.

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

It is not a de Polignac number, because 21899855 - 2¹² = 21895759 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2189981 + ... + 2189990.

It is an arithmetic number, because the mean of its divisors is an integer number (6569958).

Almost surely, 2^21899855 is an apocalyptic number.

21899855 is a deficient number, since it is larger than the sum of its proper divisors (4379977).

21899855 is an equidigital number, since it uses as much as digits as its factorization.

21899855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4379976.

The product of its digits is 259200, while the sum is 47.

The square root of 21899855 is about 4679.7280903916. The cubic root of 21899855 is about 279.7781192893.

The spelling of 21899855 in words is "twenty-one million, eight hundred ninety-nine thousand, eight hundred fifty-five".