28919721613 has 2 divisors, whose sum is σ = 28919721614. Its totient is φ = 28919721612.

The previous prime is 28919721569. The next prime is 28919721619. The reversal of 28919721613 is 31612791982.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26682242409 + 2237479204 = 163347^2 + 47302^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28919721613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28919721619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14459860806 + 14459860807.

It is an arithmetic number, because the mean of its divisors is an integer number (14459860807).

Almost surely, 2^28919721613 is an apocalyptic number.

It is an amenable number.

28919721613 is a deficient number, since it is larger than the sum of its proper divisors (1).

28919721613 is an equidigital number, since it uses as much as digits as its factorization.

28919721613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 49.

The spelling of 28919721613 in words is "twenty-eight billion, nine hundred nineteen million, seven hundred twenty-one thousand, six hundred thirteen".