21399385 has 8 divisors (see below), whose sum is σ = 29347776. Its totient is φ = 14673840.

The previous prime is 21399353. The next prime is 21399401. The reversal of 21399385 is 58399312.

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

It is not a de Polignac number, because 21399385 - 2⁵ = 21399353 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 305671 + ... + 305740.

It is an arithmetic number, because the mean of its divisors is an integer number (3668472).

Almost surely, 2^21399385 is an apocalyptic number.

It is an amenable number.

21399385 is a deficient number, since it is larger than the sum of its proper divisors (7948391).

21399385 is an equidigital number, since it uses as much as digits as its factorization.

21399385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 611423.

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

The square root of 21399385 is about 4625.9469300890. The cubic root of 21399385 is about 277.6304502596.

The spelling of 21399385 in words is "twenty-one million, three hundred ninety-nine thousand, three hundred eighty-five".