390921793 has 6 divisors (see below), whose sum is σ = 393773874. Its totient is φ = 388090224.

The previous prime is 390921781. The next prime is 390921803. The reversal of 390921793 is 397129093.

It can be written as a sum of positive squares in only one way, i.e., 336649104 + 54272689 = 18348^2 + 7367^2 .

It is not a de Polignac number, because 390921793 - 2²¹ = 388824641 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (390921893) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9205 + ... + 29437.

It is an arithmetic number, because the mean of its divisors is an integer number (65628979).

Almost surely, 2^390921793 is an apocalyptic number.

It is an amenable number.

390921793 is a deficient number, since it is larger than the sum of its proper divisors (2852081).

390921793 is an equidigital number, since it uses as much as digits as its factorization.

390921793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20511 (or 20372 counting only the distinct ones).

The product of its (nonzero) digits is 91854, while the sum is 43.

The square root of 390921793 is about 19771.7422853931. The cubic root of 390921793 is about 731.1895243239.

The spelling of 390921793 in words is "three hundred ninety million, nine hundred twenty-one thousand, seven hundred ninety-three".