1620400813 has 2 divisors, whose sum is σ = 1620400814. Its totient is φ = 1620400812.

The previous prime is 1620400801. The next prime is 1620400819. The reversal of 1620400813 is 3180040261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1285437609 + 334963204 = 35853^2 + 18302^2 .

It is a cyclic number.

It is not a de Polignac number, because 1620400813 - 2²⁵ = 1586846381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1620400819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810200406 + 810200407.

It is an arithmetic number, because the mean of its divisors is an integer number (810200407).

Almost surely, 2^1620400813 is an apocalyptic number.

It is an amenable number.

1620400813 is a deficient number, since it is larger than the sum of its proper divisors (1).

1620400813 is an equidigital number, since it uses as much as digits as its factorization.

1620400813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 1620400813 is about 40254.2024265790. The cubic root of 1620400813 is about 1174.5571442305.

The spelling of 1620400813 in words is "one billion, six hundred twenty million, four hundred thousand, eight hundred thirteen".