21731527811 has 4 divisors (see below), whose sum is σ = 24836031792. Its totient is φ = 18627023832.

The previous prime is 21731527747. The next prime is 21731527819. The reversal of 21731527811 is 11872513712.

It is a happy number.

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 21731527811 - 2⁶ = 21731527747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21731527819) 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, 1552251980 + ... + 1552251993.

It is an arithmetic number, because the mean of its divisors is an integer number (6209007948).

Almost surely, 2^21731527811 is an apocalyptic number.

21731527811 is a deficient number, since it is larger than the sum of its proper divisors (3104503981).

21731527811 is an equidigital number, since it uses as much as digits as its factorization.

21731527811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3104503980.

The product of its digits is 23520, while the sum is 38.

The spelling of 21731527811 in words is "twenty-one billion, seven hundred thirty-one million, five hundred twenty-seven thousand, eight hundred eleven".