390921994 has 4 divisors (see below), whose sum is σ = 586382994. Its totient is φ = 195460996.

The previous prime is 390921991. The next prime is 390922009. The reversal of 390921994 is 499129093.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 499129093 = 1009 ⋅494677.

It can be written as a sum of positive squares in only one way, i.e., 278455969 + 112466025 = 16687^2 + 10605^2 .

It is not an unprimeable number, because it can be changed into a prime (390921991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97730497 + ... + 97730500.

Almost surely, 2^390921994 is an apocalyptic number.

390921994 is a deficient number, since it is larger than the sum of its proper divisors (195461000).

390921994 is a wasteful number, since it uses less digits than its factorization.

390921994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195460999.

The product of its (nonzero) digits is 157464, while the sum is 46.

The square root of 390921994 is about 19771.7473684042. The cubic root of 390921994 is about 731.1896496423.

The spelling of 390921994 in words is "three hundred ninety million, nine hundred twenty-one thousand, nine hundred ninety-four".