1999971601 has 4 divisors (see below), whose sum is σ = 2086926912. Its totient is φ = 1913016292.

The previous prime is 1999971593. The next prime is 1999971607. The reversal of 1999971601 is 1061799991.

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 1999971601 - 2³ = 1999971593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1999971607) 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, 43477621 + ... + 43477666.

It is an arithmetic number, because the mean of its divisors is an integer number (521731728).

Almost surely, 2^1999971601 is an apocalyptic number.

It is an amenable number.

1999971601 is a deficient number, since it is larger than the sum of its proper divisors (86955311).

1999971601 is an equidigital number, since it uses as much as digits as its factorization.

1999971601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86955310.

The product of its (nonzero) digits is 275562, while the sum is 52.

The square root of 1999971601 is about 44721.0420383962. The cubic root of 1999971601 is about 1259.9150864503.

The spelling of 1999971601 in words is "one billion, nine hundred ninety-nine million, nine hundred seventy-one thousand, six hundred one".