391221900 has 90 divisors (see below), whose sum is σ = 1268213100. Its totient is φ = 104323680.

The previous prime is 391221889. The next prime is 391221923. The reversal of 391221900 is 9122193.

It is a tau number, because it is divible by the number of its divisors (90).

It is a super-2 number, since 2×391221900² = 306109150079220000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 16050 + ... + 32249.

Almost surely, 2^391221900 is an apocalyptic number.

391221900 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

391221900 is an abundant number, since it is smaller than the sum of its proper divisors (876991200).

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

391221900 is a wasteful number, since it uses less digits than its factorization.

391221900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48325 (or 48309 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 391221900 is about 19779.3301201027. The cubic root of 391221900 is about 731.3765855808.

The spelling of 391221900 in words is "three hundred ninety-one million, two hundred twenty-one thousand, nine hundred".