390506993 has 4 divisors (see below), whose sum is σ = 392489460. Its totient is φ = 388524528.

The previous prime is 390506971. The next prime is 390506999. The reversal of 390506993 is 399605093.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 239413729 + 151093264 = 15473^2 + 12292^2 .

It is a cyclic number.

It is not a de Polignac number, because 390506993 - 2⁶ = 390506929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (390506999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 990938 + ... + 991331.

It is an arithmetic number, because the mean of its divisors is an integer number (98122365).

Almost surely, 2^390506993 is an apocalyptic number.

It is an amenable number.

390506993 is a deficient number, since it is larger than the sum of its proper divisors (1982467).

390506993 is a wasteful number, since it uses less digits than its factorization.

390506993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1982466.

The product of its (nonzero) digits is 196830, while the sum is 44.

The square root of 390506993 is about 19761.2497833513. The cubic root of 390506993 is about 730.9308154996.

The spelling of 390506993 in words is "three hundred ninety million, five hundred six thousand, nine hundred ninety-three".