21055699 has 4 divisors (see below), whose sum is σ = 24063664. Its totient is φ = 18047736.

The previous prime is 21055691. The next prime is 21055703. The reversal of 21055699 is 99655012.

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

It is not a de Polignac number, because 21055699 - 2³ = 21055691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21055691) 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, 1503972 + ... + 1503985.

It is an arithmetic number, because the mean of its divisors is an integer number (6015916).

Almost surely, 2^21055699 is an apocalyptic number.

21055699 is a deficient number, since it is larger than the sum of its proper divisors (3007965).

21055699 is an equidigital number, since it uses as much as digits as its factorization.

21055699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3007964.

The product of its (nonzero) digits is 24300, while the sum is 37.

The square root of 21055699 is about 4588.6489296960. The cubic root of 21055699 is about 276.1361218552.

The spelling of 21055699 in words is "twenty-one million, fifty-five thousand, six hundred ninety-nine".