81220604 has 6 divisors (see below), whose sum is σ = 142136064. Its totient is φ = 40610300.

The previous prime is 81220591. The next prime is 81220609. The reversal of 81220604 is 40602218.

It is a self number, because there is not a number n which added to its sum of digits gives 81220604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81220609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10152572 + ... + 10152579.

It is an arithmetic number, because the mean of its divisors is an integer number (23689344).

Almost surely, 2^81220604 is an apocalyptic number.

It is an amenable number.

81220604 is a deficient number, since it is larger than the sum of its proper divisors (60915460).

81220604 is a wasteful number, since it uses less digits than its factorization.

81220604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20305155 (or 20305153 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 81220604 is about 9012.2474444502. The cubic root of 81220604 is about 433.0673125960.

The spelling of 81220604 in words is "eighty-one million, two hundred twenty thousand, six hundred four".