21395799 has 16 divisors (see below), whose sum is σ = 31768800. Its totient is φ = 14231808.

The previous prime is 21395791. The next prime is 21395821. The reversal of 21395799 is 99759312.

It is a happy number.

It is not a de Polignac number, because 21395799 - 2³ = 21395791 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21395791) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22567 + ... + 23495.

It is an arithmetic number, because the mean of its divisors is an integer number (1985550).

Almost surely, 2^21395799 is an apocalyptic number.

21395799 is a deficient number, since it is larger than the sum of its proper divisors (10373001).

21395799 is an equidigital number, since it uses as much as digits as its factorization.

21395799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1791 (or 1785 counting only the distinct ones).

The product of its digits is 153090, while the sum is 45.

The square root of 21395799 is about 4625.5593175312. The cubic root of 21395799 is about 277.6149414274.

The spelling of 21395799 in words is "twenty-one million, three hundred ninety-five thousand, seven hundred ninety-nine".