21431328787 has 32 divisors (see below), whose sum is σ = 24829009920. Its totient is φ = 18294232320.

The previous prime is 21431328781. The next prime is 21431328839. The reversal of 21431328787 is 78782313412.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21431328787 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21431328781) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12886318 + ... + 12887980.

It is an arithmetic number, because the mean of its divisors is an integer number (775906560).

Almost surely, 2^21431328787 is an apocalyptic number.

21431328787 is a deficient number, since it is larger than the sum of its proper divisors (3397681133).

21431328787 is a wasteful number, since it uses less digits than its factorization.

21431328787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2203.

The product of its digits is 451584, while the sum is 46.

The spelling of 21431328787 in words is "twenty-one billion, four hundred thirty-one million, three hundred twenty-eight thousand, seven hundred eighty-seven".