1916721613 has 4 divisors (see below), whose sum is σ = 1949208480. Its totient is φ = 1884234748.

The previous prime is 1916721607. The next prime is 1916721637. The reversal of 1916721613 is 3161276191.

It is a happy number.

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 1916721613 - 2⁵ = 1916721581 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 (1916721673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16243345 + ... + 16243462.

It is an arithmetic number, because the mean of its divisors is an integer number (487302120).

Almost surely, 2^1916721613 is an apocalyptic number.

It is an amenable number.

1916721613 is a deficient number, since it is larger than the sum of its proper divisors (32486867).

1916721613 is an equidigital number, since it uses as much as digits as its factorization.

1916721613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32486866.

The product of its digits is 13608, while the sum is 37.

The square root of 1916721613 is about 43780.3793153965. The cubic root of 1916721613 is about 1242.1851889043.

The spelling of 1916721613 in words is "one billion, nine hundred sixteen million, seven hundred twenty-one thousand, six hundred thirteen".