21358993 has 8 divisors (see below), whose sum is σ = 22377600. Its totient is φ = 20359248.

The previous prime is 21358979. The next prime is 21358999. The reversal of 21358993 is 39985312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21358993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21358999) 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, 2371 + ... + 6952.

It is an arithmetic number, because the mean of its divisors is an integer number (2797200).

Almost surely, 2^21358993 is an apocalyptic number.

It is an amenable number.

21358993 is a deficient number, since it is larger than the sum of its proper divisors (1018607).

21358993 is an equidigital number, since it uses as much as digits as its factorization.

21358993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9431.

The product of its digits is 58320, while the sum is 40.

The square root of 21358993 is about 4621.5790591528. The cubic root of 21358993 is about 277.4556615577.

The spelling of 21358993 in words is "twenty-one million, three hundred fifty-eight thousand, nine hundred ninety-three".