21031431505 has 8 divisors (see below), whose sum is σ = 28843106112. Its totient is φ = 14421553008.

The previous prime is 21031431497. The next prime is 21031431511. The reversal of 21031431505 is 50513413012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21031431505 - 2³ = 21031431497 is a prime.

It is a super-2 number, since 2×21031431505² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21031431505.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 300448987 + ... + 300449056.

It is an arithmetic number, because the mean of its divisors is an integer number (3605388264).

Almost surely, 2^21031431505 is an apocalyptic number.

It is an amenable number.

21031431505 is a deficient number, since it is larger than the sum of its proper divisors (7811674607).

21031431505 is an equidigital number, since it uses as much as digits as its factorization.

21031431505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 600898055.

The product of its (nonzero) digits is 1800, while the sum is 25.

Adding to 21031431505 its reverse (50513413012), we get a palindrome (71544844517).

The spelling of 21031431505 in words is "twenty-one billion, thirty-one million, four hundred thirty-one thousand, five hundred five".