81635139068 has 24 divisors (see below), whose sum is σ = 172874413152. Its totient is φ = 32928459264.

The previous prime is 81635139059. The next prime is 81635139077. The reversal of 81635139068 is 86093153618.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81635139059) and next prime (81635139077).

It is a super-3 number, since 3×81635139068³ (a number of 34 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (50) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85750721 + ... + 85751672.

It is an arithmetic number, because the mean of its divisors is an integer number (7203100548).

Almost surely, 2^81635139068 is an apocalyptic number.

It is an amenable number.

81635139068 is an abundant number, since it is smaller than the sum of its proper divisors (91239274084).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81635139068 is a wasteful number, since it uses less digits than its factorization.

81635139068 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171502421 (or 171502419 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 50.

The spelling of 81635139068 in words is "eighty-one billion, six hundred thirty-five million, one hundred thirty-nine thousand, sixty-eight".