21431434243 has 4 divisors (see below), whose sum is σ = 21725015608. Its totient is φ = 21137852880.

The previous prime is 21431434163. The next prime is 21431434253. The reversal of 21431434243 is 34243413412.

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 21431434243 - 2⁹ = 21431433731 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21431434253) 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, 146790573 + ... + 146790718.

It is an arithmetic number, because the mean of its divisors is an integer number (5431253902).

Almost surely, 2^21431434243 is an apocalyptic number.

21431434243 is a deficient number, since it is larger than the sum of its proper divisors (293581365).

21431434243 is an equidigital number, since it uses as much as digits as its factorization.

21431434243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293581364.

The product of its digits is 27648, while the sum is 31.

Adding to 21431434243 its reverse (34243413412), we get a palindrome (55674847655).

The spelling of 21431434243 in words is "twenty-one billion, four hundred thirty-one million, four hundred thirty-four thousand, two hundred forty-three".