81667220 has 12 divisors (see below), whose sum is σ = 171501204. Its totient is φ = 32666880.

The previous prime is 81667213. The next prime is 81667241. The reversal of 81667220 is 2276618.

It can be written as a sum of positive squares in 2 ways, for example, as 17859076 + 63808144 = 4226^2 + 7988^2 .

It is a hoax number, since the sum of its digits (32) 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 3 ways as a sum of consecutive naturals, for example, 2041661 + ... + 2041700.

It is an arithmetic number, because the mean of its divisors is an integer number (14291767).

Almost surely, 2^81667220 is an apocalyptic number.

It is an amenable number.

81667220 is an abundant number, since it is smaller than the sum of its proper divisors (89833984).

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

81667220 is a wasteful number, since it uses less digits than its factorization.

81667220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4083370 (or 4083368 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 81667220 is about 9036.9917561100. The cubic root of 81667220 is about 433.8596458378.

The spelling of 81667220 in words is "eighty-one million, six hundred sixty-seven thousand, two hundred twenty".