18721272 has 32 divisors (see below), whose sum is σ = 48314880. Its totient is φ = 6038880.

The previous prime is 18721271. The next prime is 18721273. The reversal of 18721272 is 27212781.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18721271) and next prime (18721273).

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18721271) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11838 + ... + 13325.

It is an arithmetic number, because the mean of its divisors is an integer number (1509840).

Almost surely, 2^18721272 is an apocalyptic number.

18721272 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

18721272 is an abundant number, since it is smaller than the sum of its proper divisors (29593608).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18721272 is a wasteful number, since it uses less digits than its factorization.

18721272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25203 (or 25199 counting only the distinct ones).

The product of its digits is 3136, while the sum is 30.

The square root of 18721272 is about 4326.8085236118. The cubic root of 18721272 is about 265.5288926959.

The spelling of 18721272 in words is "eighteen million, seven hundred twenty-one thousand, two hundred seventy-two".