21420599 has 4 divisors (see below), whose sum is σ = 21783720. Its totient is φ = 21057480.

The previous prime is 21420587. The next prime is 21420643. The reversal of 21420599 is 99502412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21420599 - 2¹² = 21416503 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 (21420569) 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, 181472 + ... + 181589.

It is an arithmetic number, because the mean of its divisors is an integer number (5445930).

Almost surely, 2^21420599 is an apocalyptic number.

21420599 is a deficient number, since it is larger than the sum of its proper divisors (363121).

21420599 is an equidigital number, since it uses as much as digits as its factorization.

21420599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363120.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 21420599 is about 4628.2392980484. The cubic root of 21420599 is about 277.7221617306.

The spelling of 21420599 in words is "twenty-one million, four hundred twenty thousand, five hundred ninety-nine".