1995613721 has 4 divisors (see below), whose sum is σ = 1996454244. Its totient is φ = 1994773200.

The previous prime is 1995613679. The next prime is 1995613723. The reversal of 1995613721 is 1273165991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 153487321 + 1842126400 = 12389^2 + 42920^2 .

It is a cyclic number.

It is not a de Polignac number, because 1995613721 - 2⁶ = 1995613657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1995613723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 416690 + ... + 421451.

It is an arithmetic number, because the mean of its divisors is an integer number (499113561).

Almost surely, 2^1995613721 is an apocalyptic number.

It is an amenable number.

1995613721 is a deficient number, since it is larger than the sum of its proper divisors (840523).

1995613721 is an equidigital number, since it uses as much as digits as its factorization.

1995613721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 840522.

The product of its digits is 102060, while the sum is 44.

The square root of 1995613721 is about 44672.2925424698. The cubic root of 1995613721 is about 1258.9993148611. Note that the first 3 decimals are identical.

The spelling of 1995613721 in words is "one billion, nine hundred ninety-five million, six hundred thirteen thousand, seven hundred twenty-one".