81628436 has 12 divisors (see below), whose sum is σ = 143893428. Its totient is φ = 40516032.

The previous prime is 81628429. The next prime is 81628457. The reversal of 81628436 is 63482618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 38987536 + 42640900 = 6244^2 + 6530^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81628436.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73931 + ... + 75026.

It is an arithmetic number, because the mean of its divisors is an integer number (11991119).

Almost surely, 2^81628436 is an apocalyptic number.

It is an amenable number.

81628436 is a deficient number, since it is larger than the sum of its proper divisors (62264992).

81628436 is a wasteful number, since it uses less digits than its factorization.

81628436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149098 (or 149096 counting only the distinct ones).

The product of its digits is 55296, while the sum is 38.

The square root of 81628436 is about 9034.8456544647. The cubic root of 81628436 is about 433.7909545608.

The spelling of 81628436 in words is "eighty-one million, six hundred twenty-eight thousand, four hundred thirty-six".