21333997 has 4 divisors (see below), whose sum is σ = 22588956. Its totient is φ = 20079040.

The previous prime is 21333973. The next prime is 21334007. The reversal of 21333997 is 79933312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7241481 + 14092516 = 2691^2 + 3754^2 .

It is not a de Polignac number, because 21333997 - 2¹⁵ = 21301229 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 (21333947) 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, 627454 + ... + 627487.

It is an arithmetic number, because the mean of its divisors is an integer number (5647239).

Almost surely, 2^21333997 is an apocalyptic number.

It is an amenable number.

21333997 is a deficient number, since it is larger than the sum of its proper divisors (1254959).

21333997 is a wasteful number, since it uses less digits than its factorization.

21333997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1254958.

The product of its digits is 30618, while the sum is 37.

The square root of 21333997 is about 4618.8739969824. The cubic root of 21333997 is about 277.3473857152.

The spelling of 21333997 in words is "twenty-one million, three hundred thirty-three thousand, nine hundred ninety-seven".