19811664631 has 4 divisors (see below), whose sum is σ = 21612725064. Its totient is φ = 18010604200.

The previous prime is 19811664623. The next prime is 19811664643. The reversal of 19811664631 is 13646611891.

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

It is a cyclic number.

It is not a de Polignac number, because 19811664631 - 2³ = 19811664623 is a prime.

It is a super-2 number, since 2×19811664631² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19811664601) 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 3 ways as a sum of consecutive naturals, for example, 900530200 + ... + 900530221.

It is an arithmetic number, because the mean of its divisors is an integer number (5403181266).

Almost surely, 2^19811664631 is an apocalyptic number.

19811664631 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

19811664631 is a deficient number, since it is larger than the sum of its proper divisors (1801060433).

19811664631 is a wasteful number, since it uses less digits than its factorization.

19811664631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1801060432.

The product of its digits is 186624, while the sum is 46.

The spelling of 19811664631 in words is "nineteen billion, eight hundred eleven million, six hundred sixty-four thousand, six hundred thirty-one".