18476721 has 16 divisors (see below), whose sum is σ = 28814400. Its totient is φ = 11669184.

The previous prime is 18476707. The next prime is 18476723. The reversal of 18476721 is 12767481.

It is not a de Polignac number, because 18476721 - 2²¹ = 16379569 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18476723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17496 + ... + 18521.

It is an arithmetic number, because the mean of its divisors is an integer number (1800900).

Almost surely, 2^18476721 is an apocalyptic number.

It is an amenable number.

18476721 is a deficient number, since it is larger than the sum of its proper divisors (10337679).

18476721 is a wasteful number, since it uses less digits than its factorization.

18476721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36045 (or 36039 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 18476721 is about 4298.4556529061. The cubic root of 18476721 is about 264.3676437770.

The spelling of 18476721 in words is "eighteen million, four hundred seventy-six thousand, seven hundred twenty-one".