15640999993 has 2 divisors, whose sum is σ = 15640999994. Its totient is φ = 15640999992.

The previous prime is 15640999949. The next prime is 15641000021. The reversal of 15640999993 is 39999904651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14072602384 + 1568397609 = 118628^2 + 39603^2 .

It is a cyclic number.

It is not a de Polignac number, because 15640999993 - 2¹³ = 15640991801 is a prime.

It is not a weakly prime, because it can be changed into another prime (15640999193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7820499996 + 7820499997.

It is an arithmetic number, because the mean of its divisors is an integer number (7820499997).

Almost surely, 2^15640999993 is an apocalyptic number.

It is an amenable number.

15640999993 is a deficient number, since it is larger than the sum of its proper divisors (1).

15640999993 is an equidigital number, since it uses as much as digits as its factorization.

15640999993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21257640, while the sum is 64.

The spelling of 15640999993 in words is "fifteen billion, six hundred forty million, nine hundred ninety-nine thousand, nine hundred ninety-three".