1389595721 has 2 divisors, whose sum is σ = 1389595722. Its totient is φ = 1389595720.

The previous prime is 1389595699. The next prime is 1389595751. The reversal of 1389595721 is 1275959831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1388605696 + 990025 = 37264^2 + 995^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1389595721 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1389595721.

It is not a weakly prime, because it can be changed into another prime (1389595751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 694797860 + 694797861.

It is an arithmetic number, because the mean of its divisors is an integer number (694797861).

Almost surely, 2^1389595721 is an apocalyptic number.

It is an amenable number.

1389595721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1389595721 is an equidigital number, since it uses as much as digits as its factorization.

1389595721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 680400, while the sum is 50.

The square root of 1389595721 is about 37277.2815666593. The cubic root of 1389595721 is about 1115.9108220537.

The spelling of 1389595721 in words is "one billion, three hundred eighty-nine million, five hundred ninety-five thousand, seven hundred twenty-one".