21336991 has 8 divisors (see below), whose sum is σ = 23302944. Its totient is φ = 19417440.

The previous prime is 21336961. The next prime is 21337003. The reversal of 21336991 is 19963312.

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 21336991 - 2¹³ = 21328799 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 (21336961) 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, 10636 + ... + 12481.

It is an arithmetic number, because the mean of its divisors is an integer number (2912868).

Almost surely, 2^21336991 is an apocalyptic number.

21336991 is a deficient number, since it is larger than the sum of its proper divisors (1965953).

21336991 is a wasteful number, since it uses less digits than its factorization.

21336991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23201.

The product of its digits is 8748, while the sum is 34.

The square root of 21336991 is about 4619.1980905781. The cubic root of 21336991 is about 277.3603593621.

The spelling of 21336991 in words is "twenty-one million, three hundred thirty-six thousand, nine hundred ninety-one".