21329997 has 12 divisors (see below), whose sum is σ = 30796704. Its totient is φ = 13125840.

The previous prime is 21329983. The next prime is 21329999. The reversal of 21329997 is 79992312.

It is a happy number.

It is not a de Polignac number, because 21329997 - 2⁴ = 21329981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21329999) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20529 + ... + 21542.

It is an arithmetic number, because the mean of its divisors is an integer number (2566392).

Almost surely, 2^21329997 is an apocalyptic number.

It is an amenable number.

21329997 is a deficient number, since it is larger than the sum of its proper divisors (9466707).

21329997 is a wasteful number, since it uses less digits than its factorization.

21329997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42100 (or 42087 counting only the distinct ones).

The product of its digits is 61236, while the sum is 42.

The square root of 21329997 is about 4618.4409707173. The cubic root of 21329997 is about 277.3300509594.

The spelling of 21329997 in words is "twenty-one million, three hundred twenty-nine thousand, nine hundred ninety-seven".