1991629145 has 12 divisors (see below), whose sum is σ = 2626976100. Its totient is φ = 1448457120.

The previous prime is 1991629127. The next prime is 1991629187. The reversal of 1991629145 is 5419261991.

It can be written as a sum of positive squares in 2 ways, for example, as 592046224 + 1399582921 = 24332^2 + 37411^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1991629145 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1991629145.

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 in 11 ways as a sum of consecutive naturals, for example, 1645370 + ... + 1646579.

It is an arithmetic number, because the mean of its divisors is an integer number (218914675).

Almost surely, 2^1991629145 is an apocalyptic number.

It is an amenable number.

1991629145 is a deficient number, since it is larger than the sum of its proper divisors (635346955).

1991629145 is a wasteful number, since it uses less digits than its factorization.

1991629145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3291976 (or 3291965 counting only the distinct ones).

The product of its digits is 174960, while the sum is 47.

The square root of 1991629145 is about 44627.6724129771. The cubic root of 1991629145 is about 1258.1608224345.

It can be divided in two parts, 1991 and 629145, that added together give a palindrome (631136).

The spelling of 1991629145 in words is "one billion, nine hundred ninety-one million, six hundred twenty-nine thousand, one hundred forty-five".