1630991991 has 8 divisors (see below), whose sum is σ = 2178183024. Its totient is φ = 1085564480.

The previous prime is 1630991983. The next prime is 1630991993. The reversal of 1630991991 is 1991990361.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1630991991 - 2³ = 1630991983 is a prime.

It is a super-2 number, since 2×1630991991² = 5320269749412288162, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1630991991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1630991993) 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 7 ways as a sum of consecutive naturals, for example, 438720 + ... + 442421.

It is an arithmetic number, because the mean of its divisors is an integer number (272272878).

Almost surely, 2^1630991991 is an apocalyptic number.

1630991991 is a deficient number, since it is larger than the sum of its proper divisors (547191033).

1630991991 is an equidigital number, since it uses as much as digits as its factorization.

1630991991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 881761.

The product of its (nonzero) digits is 118098, while the sum is 48.

The square root of 1630991991 is about 40385.5418559662. The cubic root of 1630991991 is about 1177.1106150704.

The spelling of 1630991991 in words is "one billion, six hundred thirty million, nine hundred ninety-one thousand, nine hundred ninety-one".