1991943802 has 4 divisors (see below), whose sum is σ = 2987915706. Its totient is φ = 995971900.

The previous prime is 1991943787. The next prime is 1991943817. The reversal of 1991943802 is 2083491991.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (1991943787) and next prime (1991943817).

It can be written as a sum of positive squares in only one way, i.e., 1141696521 + 850247281 = 33789^2 + 29159^2 .

It is a super-2 number, since 2×1991943802² = 7935680220652430408, which contains 22 as substring.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 497985949 + ... + 497985952.

Almost surely, 2^1991943802 is an apocalyptic number.

1991943802 is a deficient number, since it is larger than the sum of its proper divisors (995971904).

1991943802 is an equidigital number, since it uses as much as digits as its factorization.

1991943802 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 995971903.

The product of its (nonzero) digits is 139968, while the sum is 46.

The square root of 1991943802 is about 44631.1976312534. The cubic root of 1991943802 is about 1258.2270777853.

The spelling of 1991943802 in words is "one billion, nine hundred ninety-one million, nine hundred forty-three thousand, eight hundred two".