18689991437 has 16 divisors (see below), whose sum is σ = 21333724272. Its totient is φ = 16220651520.

The previous prime is 18689991433. The next prime is 18689991443. The reversal of 18689991437 is 73419998681.

It can be written as a sum of positive squares in 8 ways, for example, as 165148201 + 18524843236 = 12851^2 + 136106^2 .

It is a cyclic number.

It is not a de Polignac number, because 18689991437 - 2² = 18689991433 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18689991431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 172637 + ... + 259197.

It is an arithmetic number, because the mean of its divisors is an integer number (1333357767).

Almost surely, 2^18689991437 is an apocalyptic number.

18689991437 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

18689991437 is a deficient number, since it is larger than the sum of its proper divisors (2643732835).

18689991437 is a wasteful number, since it uses less digits than its factorization.

18689991437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87568.

The product of its digits is 23514624, while the sum is 65.

The spelling of 18689991437 in words is "eighteen billion, six hundred eighty-nine million, nine hundred ninety-one thousand, four hundred thirty-seven".