129820813 has 4 divisors (see below), whose sum is σ = 129843648. Its totient is φ = 129797980.

The previous prime is 129820807. The next prime is 129820877. The reversal of 129820813 is 318028921.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 318028921 = 7 ⋅45432703.

It is a cyclic number.

It is not a de Polignac number, because 129820813 - 2⁵ = 129820781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129820213) 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, 4620 + ... + 16762.

It is an arithmetic number, because the mean of its divisors is an integer number (32460912).

Almost surely, 2^129820813 is an apocalyptic number.

It is an amenable number.

129820813 is a deficient number, since it is larger than the sum of its proper divisors (22835).

129820813 is a wasteful number, since it uses less digits than its factorization.

129820813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22834.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 129820813 is about 11393.8936716120. The cubic root of 129820813 is about 506.3468448978.

The spelling of 129820813 in words is "one hundred twenty-nine million, eight hundred twenty thousand, eight hundred thirteen".