21112505431 has 2 divisors, whose sum is σ = 21112505432. Its totient is φ = 21112505430.

The previous prime is 21112505429. The next prime is 21112505459. The reversal of 21112505431 is 13450521112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21112505431 - 2¹ = 21112505429 is a prime.

It is a super-2 number, since 2×21112505431² (a number of 21 digits) contains 22 as substring.

Together with 21112505429, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21112505396 and 21112505405.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21112505461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556252715 + 10556252716.

It is an arithmetic number, because the mean of its divisors is an integer number (10556252716).

Almost surely, 2^21112505431 is an apocalyptic number.

21112505431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112505431 is an equidigital number, since it uses as much as digits as its factorization.

21112505431 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1200, while the sum is 25.

The spelling of 21112505431 in words is "twenty-one billion, one hundred twelve million, five hundred five thousand, four hundred thirty-one".