21205102399 has 16 divisors (see below), whose sum is σ = 24115553280. Its totient is φ = 18484040160.

The previous prime is 21205102397. The next prime is 21205102417. The reversal of 21205102399 is 99320150212.

It is a cyclic number.

It is not a de Polignac number, because 21205102399 - 2¹ = 21205102397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205102393) 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, 61207 + ... + 214840.

It is an arithmetic number, because the mean of its divisors is an integer number (1507222080).

Almost surely, 2^21205102399 is an apocalyptic number.

21205102399 is a deficient number, since it is larger than the sum of its proper divisors (2910450881).

21205102399 is a wasteful number, since it uses less digits than its factorization.

21205102399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 276390.

The product of its (nonzero) digits is 9720, while the sum is 34.

The spelling of 21205102399 in words is "twenty-one billion, two hundred five million, one hundred two thousand, three hundred ninety-nine".