15391993 has 2 divisors, whose sum is σ = 15391994. Its totient is φ = 15391992.

The previous prime is 15391931. The next prime is 15392009. The reversal of 15391993 is 39919351.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10778089 + 4613904 = 3283^2 + 2148^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15391993 is a prime.

It is not a weakly prime, because it can be changed into another prime (15391913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7695996 + 7695997.

It is an arithmetic number, because the mean of its divisors is an integer number (7695997).

Almost surely, 2^15391993 is an apocalyptic number.

It is an amenable number.

15391993 is a deficient number, since it is larger than the sum of its proper divisors (1).

15391993 is an equidigital number, since it uses as much as digits as its factorization.

15391993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32805, while the sum is 40.

The square root of 15391993 is about 3923.2630551621. The cubic root of 15391993 is about 248.7510670560.

It can be divided in two parts, 15391 and 993, that added together give a 14-th power (16384 = 2¹⁴).

The spelling of 15391993 in words is "fifteen million, three hundred ninety-one thousand, nine hundred ninety-three".