21933997 has 4 divisors (see below), whose sum is σ = 22347900. Its totient is φ = 21520096.

The previous prime is 21933971. The next prime is 21934013. The reversal of 21933997 is 79933912.

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 19900521 + 2033476 = 4461^2 + 1426^2 .

It is a cyclic number.

It is not a de Polignac number, because 21933997 - 2⁷ = 21933869 is a prime.

It is a super-2 number, since 2×21933997² = 962200448792018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21933907) 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, 206872 + ... + 206977.

It is an arithmetic number, because the mean of its divisors is an integer number (5586975).

Almost surely, 2^21933997 is an apocalyptic number.

It is an amenable number.

21933997 is a deficient number, since it is larger than the sum of its proper divisors (413903).

21933997 is an equidigital number, since it uses as much as digits as its factorization.

21933997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 413902.

The product of its digits is 91854, while the sum is 43.

The square root of 21933997 is about 4683.3745312541. The cubic root of 21933997 is about 279.9234356985.

The spelling of 21933997 in words is "twenty-one million, nine hundred thirty-three thousand, nine hundred ninety-seven".