18921072 has 40 divisors (see below), whose sum is σ = 49925376. Its totient is φ = 6172096.

The previous prime is 18921047. The next prime is 18921073. The reversal of 18921072 is 27012981.

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 (18921073) 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, 1938 + ... + 6449.

Almost surely, 2^18921072 is an apocalyptic number.

18921072 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

18921072 is an abundant number, since it is smaller than the sum of its proper divisors (31004304).

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

18921072 is a wasteful number, since it uses less digits than its factorization.

18921072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8445 (or 8439 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 18921072 is about 4349.8358589722. The cubic root of 18921072 is about 266.4701580046.

The spelling of 18921072 in words is "eighteen million, nine hundred twenty-one thousand, seventy-two".