81761550 has 96 divisors (see below), whose sum is σ = 227985408. Its totient is φ = 19240320.

The previous prime is 81761549. The next prime is 81761569. The reversal of 81761550 is 5516718.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 43939 + ... + 45761.

It is an arithmetic number, because the mean of its divisors is an integer number (2374848).

Almost surely, 2^81761550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81761550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113992704).

81761550 is an abundant number, since it is smaller than the sum of its proper divisors (146223858).

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

81761550 is a wasteful number, since it uses less digits than its factorization.

81761550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1874 (or 1869 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 33.

The square root of 81761550 is about 9042.2093539135. The cubic root of 81761550 is about 434.0266252504.

The spelling of 81761550 in words is "eighty-one million, seven hundred sixty-one thousand, five hundred fifty".