16621820 has 12 divisors (see below), whose sum is σ = 34905864. Its totient is φ = 6648720.

The previous prime is 16621811. The next prime is 16621841. The reversal of 16621820 is 2812661.

It is a super-2 number, since 2×16621820² = 552569800224800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16621820.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 415526 + ... + 415565.

It is an arithmetic number, because the mean of its divisors is an integer number (2908822).

Almost surely, 2^16621820 is an apocalyptic number.

16621820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16621820 is an abundant number, since it is smaller than the sum of its proper divisors (18284044).

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

16621820 is a wasteful number, since it uses less digits than its factorization.

16621820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 831100 (or 831098 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 16621820 is about 4076.9866323058. The cubic root of 16621820 is about 255.2071621696.

The spelling of 16621820 in words is "sixteen million, six hundred twenty-one thousand, eight hundred twenty".