18721534 has 8 divisors (see below), whose sum is σ = 30242520. Its totient is φ = 8640696.

The previous prime is 18721511. The next prime is 18721537. The reversal of 18721534 is 43512781.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 18721496 and 18721505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18721537) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 360004 + ... + 360055.

It is an arithmetic number, because the mean of its divisors is an integer number (3780315).

Almost surely, 2^18721534 is an apocalyptic number.

18721534 is a deficient number, since it is larger than the sum of its proper divisors (11520986).

18721534 is a wasteful number, since it uses less digits than its factorization.

18721534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 720074.

The product of its digits is 6720, while the sum is 31.

The square root of 18721534 is about 4326.8387998630. The cubic root of 18721534 is about 265.5301313625.

The spelling of 18721534 in words is "eighteen million, seven hundred twenty-one thousand, five hundred thirty-four".