18174005721 has 21 divisors (see below), whose sum is σ = 27254001999. Its totient is φ = 12113577216.

The previous prime is 18174005699. The next prime is 18174005743. The reversal of 18174005721 is 12750047181.

The square root of 18174005721 is 134811.

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

18174005721 is a `hidden beast` number, since 1 + 81 + 7 + 4 + 0 + 0 + 572 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (18174005699) and next prime (18174005743).

It can be written as a sum of positive squares in only one way, i.e., 6322635225 + 11851370496 = 79515^2 + 108864^2 .

It is not a de Polignac number, because 18174005721 - 2⁹ = 18174005209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18174005021) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 3637401 + ... + 3642393.

It is an arithmetic number, because the mean of its divisors is an integer number (1297809619).

Almost surely, 2^18174005721 is an apocalyptic number.

18174005721 is the 134811-st square number.

18174005721 is the 67406-th centered octagonal number.

It is an amenable number.

18174005721 is a deficient number, since it is larger than the sum of its proper divisors (9079996278).

18174005721 is an frugal number, since it uses more digits than its factorization.

18174005721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10004 (or 4996 counting only the distinct ones).

The product of its (nonzero) digits is 15680, while the sum is 36.

Multiplying 18174005721 by its sum of digits (36), we get a square (654264205956 = 808866²).

The spelling of 18174005721 in words is "eighteen billion, one hundred seventy-four million, five thousand, seven hundred twenty-one".