21425431531 has 4 divisors (see below), whose sum is σ = 24486207472. Its totient is φ = 18364655592.

The previous prime is 21425431519. The next prime is 21425431561. The reversal of 21425431531 is 13513452412.

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 21425431531 - 2¹¹ = 21425429483 is a prime.

It is a super-2 number, since 2×21425431531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21425431493 and 21425431502.

It is not an unprimeable number, because it can be changed into a prime (21425431561) 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, 1530387960 + ... + 1530387973.

It is an arithmetic number, because the mean of its divisors is an integer number (6121551868).

Almost surely, 2^21425431531 is an apocalyptic number.

21425431531 is a deficient number, since it is larger than the sum of its proper divisors (3060775941).

21425431531 is an equidigital number, since it uses as much as digits as its factorization.

21425431531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3060775940.

The product of its digits is 14400, while the sum is 31.

Adding to 21425431531 its reverse (13513452412), we get a palindrome (34938883943).

The spelling of 21425431531 in words is "twenty-one billion, four hundred twenty-five million, four hundred thirty-one thousand, five hundred thirty-one".