81212573 has 8 divisors (see below), whose sum is σ = 88658808. Its totient is φ = 73937664.

The previous prime is 81212561. The next prime is 81212581. The reversal of 81212573 is 37521218.

It can be written as a sum of positive squares in 4 ways, for example, as 1592644 + 79619929 = 1262^2 + 8923^2 .

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 81212573 - 2²² = 77018269 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81212503) 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, 41840 + ... + 43737.

It is an arithmetic number, because the mean of its divisors is an integer number (11082351).

Almost surely, 2^81212573 is an apocalyptic number.

It is an amenable number.

81212573 is a deficient number, since it is larger than the sum of its proper divisors (7446235).

81212573 is a wasteful number, since it uses less digits than its factorization.

81212573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85663.

The product of its digits is 3360, while the sum is 29.

The square root of 81212573 is about 9011.8018730995. The cubic root of 81212573 is about 433.0530383928.

The spelling of 81212573 in words is "eighty-one million, two hundred twelve thousand, five hundred seventy-three".