18530721 has 32 divisors (see below), whose sum is σ = 30666240. Its totient is φ = 10962000.

The previous prime is 18530713. The next prime is 18530741. The reversal of 18530721 is 12703581.

It is not a de Polignac number, because 18530721 - 2³ = 18530713 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (18530711) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12046 + ... + 13496.

It is an arithmetic number, because the mean of its divisors is an integer number (958320).

Almost surely, 2^18530721 is an apocalyptic number.

18530721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18530721 is a deficient number, since it is larger than the sum of its proper divisors (12135519).

18530721 is a wasteful number, since it uses less digits than its factorization.

18530721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1514 (or 1508 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 18530721 is about 4304.7323958639. The cubic root of 18530721 is about 264.6249399315.

The spelling of 18530721 in words is "eighteen million, five hundred thirty thousand, seven hundred twenty-one".