21904499 has 4 divisors (see below), whose sum is σ = 21918936. Its totient is φ = 21890064.

The previous prime is 21904489. The next prime is 21904523. The reversal of 21904499 is 99440912.

It is a happy number.

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 21904499 - 2¹⁶ = 21838963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21904459) 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, 4634 + ... + 8079.

It is an arithmetic number, because the mean of its divisors is an integer number (5479734).

Almost surely, 2^21904499 is an apocalyptic number.

21904499 is a deficient number, since it is larger than the sum of its proper divisors (14437).

21904499 is a wasteful number, since it uses less digits than its factorization.

21904499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14436.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21904499 is about 4680.2242467643. The cubic root of 21904499 is about 279.7978941197.

The spelling of 21904499 in words is "twenty-one million, nine hundred four thousand, four hundred ninety-nine".