18721923 has 16 divisors (see below), whose sum is σ = 28111872. Its totient is φ = 10980000.

The previous prime is 18721903. The next prime is 18721979. The reversal of 18721923 is 32912781.

It is not a de Polignac number, because 18721923 - 2⁵ = 18721891 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (18721903) 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, 8128 + ... + 10173.

It is an arithmetic number, because the mean of its divisors is an integer number (1756992).

Almost surely, 2^18721923 is an apocalyptic number.

18721923 is a deficient number, since it is larger than the sum of its proper divisors (9389949).

18721923 is a wasteful number, since it uses less digits than its factorization.

18721923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18346.

The product of its digits is 6048, while the sum is 33.

The square root of 18721923 is about 4326.8837516162. The cubic root of 18721923 is about 265.5319704302.

The spelling of 18721923 in words is "eighteen million, seven hundred twenty-one thousand, nine hundred twenty-three".