21732361561 has 3 divisors (see below), whose sum is σ = 21732508981. Its totient is φ = 21732214142.

The previous prime is 21732361513. The next prime is 21732361577. The reversal of 21732361561 is 16516323712.

The square root of 21732361561 is 147419.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a de Polignac number, because none of the positive numbers 2^k-21732361561 is a prime.

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 21732361561.

It is not an unprimeable number, because it can be changed into a prime (21732361361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 73710 + ... + 221128.

Almost surely, 2^21732361561 is an apocalyptic number.

21732361561 is the 147419-th square number.

21732361561 is the 73710-th centered octagonal number.

It is an amenable number.

21732361561 is a deficient number, since it is larger than the sum of its proper divisors (147420).

21732361561 is an frugal number, since it uses more digits than its factorization.

21732361561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 294838 (or 147419 counting only the distinct ones).

The product of its digits is 45360, while the sum is 37.

The spelling of 21732361561 in words is "twenty-one billion, seven hundred thirty-two million, three hundred sixty-one thousand, five hundred sixty-one".