19900813 has 4 divisors (see below), whose sum is σ = 19984320. Its totient is φ = 19817308.

The previous prime is 19900801. The next prime is 19900817. The reversal of 19900813 is 31800991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19900813 - 2⁵ = 19900781 is a prime.

It is a Duffinian number.

19900813 is a modest number, since divided by 813 gives 199 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19900817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41395 + ... + 41872.

It is an arithmetic number, because the mean of its divisors is an integer number (4996080).

Almost surely, 2^19900813 is an apocalyptic number.

It is an amenable number.

19900813 is a deficient number, since it is larger than the sum of its proper divisors (83507).

19900813 is an equidigital number, since it uses as much as digits as its factorization.

19900813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83506.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 19900813 is about 4461.0327279678. The cubic root of 19900813 is about 270.9922929141.

The spelling of 19900813 in words is "nineteen million, nine hundred thousand, eight hundred thirteen".