390927721 has 2 divisors, whose sum is σ = 390927722. Its totient is φ = 390927720.

The previous prime is 390927673. The next prime is 390927773. The reversal of 390927721 is 127729093.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 389628121 + 1299600 = 19739^2 + 1140^2 .

It is an emirp because it is prime and its reverse (127729093) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 390927721 - 2¹¹ = 390925673 is a prime.

It is not a weakly prime, because it can be changed into another prime (390927791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195463860 + 195463861.

It is an arithmetic number, because the mean of its divisors is an integer number (195463861).

Almost surely, 2^390927721 is an apocalyptic number.

It is an amenable number.

390927721 is a deficient number, since it is larger than the sum of its proper divisors (1).

390927721 is an equidigital number, since it uses as much as digits as its factorization.

390927721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 47628, while the sum is 40.

The square root of 390927721 is about 19771.8921957409. The cubic root of 390927721 is about 731.1932202632.

The spelling of 390927721 in words is "three hundred ninety million, nine hundred twenty-seven thousand, seven hundred twenty-one".