81261216 has 36 divisors (see below), whose sum is σ = 231087402. Its totient is φ = 27086976.

The previous prime is 81261209. The next prime is 81261239. The reversal of 81261216 is 61216218.

It can be written as a sum of positive squares in only one way, i.e., 42771600 + 38489616 = 6540^2 + 6204^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 81261216.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 140791 + ... + 141366.

Almost surely, 2^81261216 is an apocalyptic number.

It is an amenable number.

81261216 is an abundant number, since it is smaller than the sum of its proper divisors (149826186).

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

81261216 is a wasteful number, since it uses less digits than its factorization.

81261216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282173 (or 282162 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 81261216 is about 9014.5003189306. The cubic root of 81261216 is about 433.1394814720.

The spelling of 81261216 in words is "eighty-one million, two hundred sixty-one thousand, two hundred sixteen".