381637921 has 16 divisors (see below), whose sum is σ = 448614400. Its totient is φ = 324505440.

The previous prime is 381637903. The next prime is 381637937. The reversal of 381637921 is 129736183.

It is not a de Polignac number, because 381637921 - 2⁷ = 381637793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (381637961) 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, 39181 + ... + 47941.

It is an arithmetic number, because the mean of its divisors is an integer number (28038400).

Almost surely, 2^381637921 is an apocalyptic number.

It is an amenable number.

381637921 is a deficient number, since it is larger than the sum of its proper divisors (66976479).

381637921 is an equidigital number, since it uses as much as digits as its factorization.

381637921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8909 (or 8895 counting only the distinct ones).

The product of its digits is 54432, while the sum is 40.

The square root of 381637921 is about 19535.5553030878. Note that the first 3 decimals coincide. The cubic root of 381637921 is about 725.3548297194.

The spelling of 381637921 in words is "three hundred eighty-one million, six hundred thirty-seven thousand, nine hundred twenty-one".