20958400999 has 4 divisors (see below), whose sum is σ = 20961040936. Its totient is φ = 20955761064.

The previous prime is 20958400993. The next prime is 20958401039. The reversal of 20958400999 is 99900485902.

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 20958400999 - 2⁹ = 20958400487 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 (20958400993) 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, 1308024 + ... + 1323949.

It is an arithmetic number, because the mean of its divisors is an integer number (5240260234).

Almost surely, 2^20958400999 is an apocalyptic number.

20958400999 is a deficient number, since it is larger than the sum of its proper divisors (2639937).

20958400999 is an equidigital number, since it uses as much as digits as its factorization.

20958400999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2639936.

The product of its (nonzero) digits is 2099520, while the sum is 55.

The spelling of 20958400999 in words is "twenty billion, nine hundred fifty-eight million, four hundred thousand, nine hundred ninety-nine".