81906906149 has 8 divisors (see below), whose sum is σ = 83073292440. Its totient is φ = 80741719296.

The previous prime is 81906906139. The next prime is 81906906161. The reversal of 81906906149 is 94160960918.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 37044700900 + 44862205249 = 192470^2 + 211807^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81906906149 - 2¹² = 81906902053 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81906906149.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81906906139) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161864 + ... + 435905.

It is an arithmetic number, because the mean of its divisors is an integer number (10384161555).

Almost surely, 2^81906906149 is an apocalyptic number.

It is an amenable number.

81906906149 is a deficient number, since it is larger than the sum of its proper divisors (1166386291).

81906906149 is a wasteful number, since it uses less digits than its factorization.

81906906149 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 599719.

The product of its (nonzero) digits is 839808, while the sum is 53.

The spelling of 81906906149 in words is "eighty-one billion, nine hundred six million, nine hundred six thousand, one hundred forty-nine".