21400431051 has 4 divisors (see below), whose sum is σ = 28533908072. Its totient is φ = 14266954032.

The previous prime is 21400431047. The next prime is 21400431067. The reversal of 21400431051 is 15013400412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21400431051 - 2² = 21400431047 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21400431551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3566738506 + ... + 3566738511.

It is an arithmetic number, because the mean of its divisors is an integer number (7133477018).

Almost surely, 2^21400431051 is an apocalyptic number.

21400431051 is a deficient number, since it is larger than the sum of its proper divisors (7133477021).

21400431051 is an equidigital number, since it uses as much as digits as its factorization.

21400431051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7133477020.

The product of its (nonzero) digits is 480, while the sum is 21.

Adding to 21400431051 its reverse (15013400412), we get a palindrome (36413831463).

The spelling of 21400431051 in words is "twenty-one billion, four hundred million, four hundred thirty-one thousand, fifty-one".