21908999 has 8 divisors (see below), whose sum is σ = 25273728. Its totient is φ = 18603000.

The previous prime is 21908989. The next prime is 21909029. The reversal of 21908999 is 99980912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21908999 - 2⁸ = 21908743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21908959) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13877 + ... + 15374.

It is an arithmetic number, because the mean of its divisors is an integer number (3159216).

Almost surely, 2^21908999 is an apocalyptic number.

21908999 is a deficient number, since it is larger than the sum of its proper divisors (3364729).

21908999 is a wasteful number, since it uses less digits than its factorization.

21908999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29365.

The product of its (nonzero) digits is 104976, while the sum is 47.

The square root of 21908999 is about 4680.7049682713. The cubic root of 21908999 is about 279.8170531109.

The spelling of 21908999 in words is "twenty-one million, nine hundred eight thousand, nine hundred ninety-nine".