15640813 has 2 divisors, whose sum is σ = 15640814. Its totient is φ = 15640812.

The previous prime is 15640747. The next prime is 15640829. The reversal of 15640813 is 31804651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8655364 + 6985449 = 2942^2 + 2643^2 .

It is a cyclic number.

It is not a de Polignac number, because 15640813 - 2¹³ = 15632621 is a prime.

It is a super-3 number, since 3×15640813³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15644813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7820406 + 7820407.

It is an arithmetic number, because the mean of its divisors is an integer number (7820407).

Almost surely, 2^15640813 is an apocalyptic number.

It is an amenable number.

15640813 is a deficient number, since it is larger than the sum of its proper divisors (1).

15640813 is an equidigital number, since it uses as much as digits as its factorization.

15640813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 15640813 is about 3954.8467732644. The cubic root of 15640813 is about 250.0843075657.

The spelling of 15640813 in words is "fifteen million, six hundred forty thousand, eight hundred thirteen".