81621606 has 32 divisors (see below), whose sum is σ = 187459200. Its totient is φ = 23431680.

The previous prime is 81621601. The next prime is 81621623. The reversal of 81621606 is 60612618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81621601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31291 + ... + 33798.

It is an arithmetic number, because the mean of its divisors is an integer number (5858100).

Almost surely, 2^81621606 is an apocalyptic number.

81621606 is an abundant number, since it is smaller than the sum of its proper divisors (105837594).

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

81621606 is a wasteful number, since it uses less digits than its factorization.

81621606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65124.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 81621606 is about 9034.4676655573. The cubic root of 81621606 is about 433.7788555301.

It can be divided in two parts, 816 and 21606, that added together give a palindrome (22422).

The spelling of 81621606 in words is "eighty-one million, six hundred twenty-one thousand, six hundred six".