81261306 has 120 divisors (see below), whose sum is σ = 219738420. Its totient is φ = 22353408.

The previous prime is 81261293. The next prime is 81261311. The reversal of 81261306 is 60316218.

It can be written as a sum of positive squares in 2 ways, for example, as 81162081 + 99225 = 9009^2 + 315^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 81261306.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 230026 + ... + 230378.

Almost surely, 2^81261306 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81261306, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109869210).

81261306 is an abundant number, since it is smaller than the sum of its proper divisors (138477114).

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

81261306 is a wasteful number, since it uses less digits than its factorization.

81261306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410 (or 394 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 81261306 is about 9014.5053108864. The cubic root of 81261306 is about 433.1396413783.

The spelling of 81261306 in words is "eighty-one million, two hundred sixty-one thousand, three hundred six".