81737933887 has 4 divisors (see below), whose sum is σ = 82028816496. Its totient is φ = 81447051280.

The previous prime is 81737933857. The next prime is 81737933891. The reversal of 81737933887 is 78833973718.

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 81737933887 - 2⁷ = 81737933759 is a prime.

It is a super-2 number, since 2×81737933887² (a number of 23 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 (81737933857) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145440883 + ... + 145441444.

It is an arithmetic number, because the mean of its divisors is an integer number (20507204124).

Almost surely, 2^81737933887 is an apocalyptic number.

81737933887 is a deficient number, since it is larger than the sum of its proper divisors (290882609).

81737933887 is a wasteful number, since it uses less digits than its factorization.

81737933887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290882608.

The product of its digits is 42674688, while the sum is 64.

The spelling of 81737933887 in words is "eighty-one billion, seven hundred thirty-seven million, nine hundred thirty-three thousand, eight hundred eighty-seven".