18721493 has 16 divisors (see below), whose sum is σ = 21934080. Its totient is φ = 15649200.

The previous prime is 18721481. The next prime is 18721511. The reversal of 18721493 is 39412781.

It is not a de Polignac number, because 18721493 - 2⁴ = 18721477 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18721393) 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, 68948 + ... + 69218.

It is an arithmetic number, because the mean of its divisors is an integer number (1370880).

Almost surely, 2^18721493 is an apocalyptic number.

It is an amenable number.

18721493 is a deficient number, since it is larger than the sum of its proper divisors (3212587).

18721493 is a wasteful number, since it uses less digits than its factorization.

18721493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 488.

The product of its digits is 12096, while the sum is 35.

The square root of 18721493 is about 4326.8340619904. The cubic root of 18721493 is about 265.5299375261.

The spelling of 18721493 in words is "eighteen million, seven hundred twenty-one thousand, four hundred ninety-three".