21774248721 has 27 divisors (see below), whose sum is σ = 31831540923. Its totient is φ = 14342929200.

The previous prime is 21774248707. The next prime is 21774248723. The reversal of 21774248721 is 12784247712.

The square root of 21774248721 is 147561.

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

21774248721 is a `hidden beast` number, since 217 + 7 + 424 + 8 + 7 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20920440321 + 853808400 = 144639^2 + 29220^2 .

It is not a de Polignac number, because 21774248721 - 2¹⁷ = 21774117649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21774248723) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 44710740 + ... + 44711226.

Almost surely, 2^21774248721 is an apocalyptic number.

21774248721 is the 147561-st square number.

21774248721 is the 73781-st centered octagonal number.

It is an amenable number.

21774248721 is a deficient number, since it is larger than the sum of its proper divisors (10057292202).

21774248721 is an frugal number, since it uses more digits than its factorization.

21774248721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1182 (or 591 counting only the distinct ones).

The product of its digits is 351232, while the sum is 45.

The spelling of 21774248721 in words is "twenty-one billion, seven hundred seventy-four million, two hundred forty-eight thousand, seven hundred twenty-one".