21205995 has 32 divisors (see below), whose sum is σ = 36698880. Its totient is φ = 10419840.

The previous prime is 21205993. The next prime is 21205999. The reversal of 21205995 is 59950212.

It is not a de Polignac number, because 21205995 - 2¹ = 21205993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21205991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9540 + ... + 11550.

It is an arithmetic number, because the mean of its divisors is an integer number (1146840).

Almost surely, 2^21205995 is an apocalyptic number.

21205995 is a deficient number, since it is larger than the sum of its proper divisors (15492885).

21205995 is a wasteful number, since it uses less digits than its factorization.

21205995 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2075.

The product of its (nonzero) digits is 8100, while the sum is 33.

The square root of 21205995 is about 4604.9967426699. The cubic root of 21205995 is about 276.7915864648.

The spelling of 21205995 in words is "twenty-one million, two hundred five thousand, nine hundred ninety-five".