16821920 has 24 divisors (see below), whose sum is σ = 39742164. Its totient is φ = 6728704.

The previous prime is 16821913. The next prime is 16821923. The reversal of 16821920 is 2912861.

It can be written as a sum of positive squares in 2 ways, for example, as 14961424 + 1860496 = 3868^2 + 1364^2 .

It is not an unprimeable number, because it can be changed into a prime (16821923) 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, 52409 + ... + 52728.

Almost surely, 2^16821920 is an apocalyptic number.

16821920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16821920 is an abundant number, since it is smaller than the sum of its proper divisors (22920244).

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

16821920 is a wasteful number, since it uses less digits than its factorization.

16821920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105152 (or 105144 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 16821920 is about 4101.4534009300. The cubic root of 16821920 is about 256.2271746474.

The spelling of 16821920 in words is "sixteen million, eight hundred twenty-one thousand, nine hundred twenty".