19815993 has 12 divisors (see below), whose sum is σ = 30129840. Its totient is φ = 12515256.

The previous prime is 19815973. The next prime is 19816007. The reversal of 19815993 is 39951891.

It is not a de Polignac number, because 19815993 - 2⁸ = 19815737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19815953) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57771 + ... + 58112.

It is an arithmetic number, because the mean of its divisors is an integer number (2510820).

Almost surely, 2^19815993 is an apocalyptic number.

It is an amenable number.

19815993 is a deficient number, since it is larger than the sum of its proper divisors (10313847).

19815993 is a wasteful number, since it uses less digits than its factorization.

19815993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115908 (or 115905 counting only the distinct ones).

The product of its digits is 87480, while the sum is 45.

The square root of 19815993 is about 4451.5158092497. The cubic root of 19815993 is about 270.6067425062.

The spelling of 19815993 in words is "nineteen million, eight hundred fifteen thousand, nine hundred ninety-three".