18025721 has 16 divisors (see below), whose sum is σ = 21725184. Its totient is φ = 14621904.

The previous prime is 18025717. The next prime is 18025727. The reversal of 18025721 is 12752081.

It is a cyclic number.

It is not a de Polignac number, because 18025721 - 2² = 18025717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18025727) 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, 16040 + ... + 17126.

It is an arithmetic number, because the mean of its divisors is an integer number (1357824).

Almost surely, 2^18025721 is an apocalyptic number.

It is an amenable number.

18025721 is a deficient number, since it is larger than the sum of its proper divisors (3699463).

18025721 is a wasteful number, since it uses less digits than its factorization.

18025721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1220.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 18025721 is about 4245.6708539405. The cubic root of 18025721 is about 262.1989098050.

It can be divided in two parts, 18025 and 721, that multiplied together give a square (12996025 = 3605²).

The spelling of 18025721 in words is "eighteen million, twenty-five thousand, seven hundred twenty-one".