21240929399 has 4 divisors (see below), whose sum is σ = 21557958264. Its totient is φ = 20923900536.

The previous prime is 21240929393. The next prime is 21240929419. The reversal of 21240929399 is 99392904212.

It is a happy number.

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 21240929399 - 2²⁸ = 20972493943 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 (21240929393) 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, 158514332 + ... + 158514465.

It is an arithmetic number, because the mean of its divisors is an integer number (5389489566).

Almost surely, 2^21240929399 is an apocalyptic number.

21240929399 is a deficient number, since it is larger than the sum of its proper divisors (317028865).

21240929399 is an equidigital number, since it uses as much as digits as its factorization.

21240929399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 317028864.

The product of its (nonzero) digits is 629856, while the sum is 50.

The spelling of 21240929399 in words is "twenty-one billion, two hundred forty million, nine hundred twenty-nine thousand, three hundred ninety-nine".