18269721 has 12 divisors (see below), whose sum is σ = 26510848. Its totient is φ = 12123864.

The previous prime is 18269707. The next prime is 18269729. The reversal of 18269721 is 12796281.

It is not a de Polignac number, because 18269721 - 2⁵ = 18269689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18269729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2545 + ... + 6558.

Almost surely, 2^18269721 is an apocalyptic number.

It is an amenable number.

18269721 is a deficient number, since it is larger than the sum of its proper divisors (8241127).

18269721 is a wasteful number, since it uses less digits than its factorization.

18269721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9332 (or 9329 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 18269721 is about 4274.3094179060. The cubic root of 18269721 is about 263.3766716402.

The spelling of 18269721 in words is "eighteen million, two hundred sixty-nine thousand, seven hundred twenty-one".