21333691 has 6 divisors (see below), whose sum is σ = 22662740. Its totient is φ = 20078496.

The previous prime is 21333679. The next prime is 21333701. The reversal of 21333691 is 19633312.

It is not a de Polignac number, because 21333691 - 2⁵ = 21333659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21333661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36621 + ... + 37198.

Almost surely, 2^21333691 is an apocalyptic number.

21333691 is a deficient number, since it is larger than the sum of its proper divisors (1329049).

21333691 is an equidigital number, since it uses as much as digits as its factorization.

21333691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73853 (or 73836 counting only the distinct ones).

The product of its digits is 2916, while the sum is 28.

The square root of 21333691 is about 4618.8408719071. The cubic root of 21333691 is about 277.3460596829.

The spelling of 21333691 in words is "twenty-one million, three hundred thirty-three thousand, six hundred ninety-one".