21731771889 has 9 divisors (see below), whose sum is σ = 31390975993. Its totient is φ = 14487553092.

The previous prime is 21731771851. The next prime is 21731771917. The reversal of 21731771889 is 98817713712.

The square root of 21731771889 is 147417.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is a de Polignac number, because none of the positive numbers 2^k-21731771889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21731771839) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 417682 + ... + 466820.

Almost surely, 2^21731771889 is an apocalyptic number.

21731771889 is the 147417-th square number.

21731771889 is the 73709-th centered octagonal number.

It is an amenable number.

21731771889 is a deficient number, since it is larger than the sum of its proper divisors (9659204104).

21731771889 is an frugal number, since it uses more digits than its factorization.

21731771889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98284 (or 49142 counting only the distinct ones).

The product of its digits is 1185408, while the sum is 54.

The spelling of 21731771889 in words is "twenty-one billion, seven hundred thirty-one million, seven hundred seventy-one thousand, eight hundred eighty-nine".