81372100 has 18 divisors (see below), whose sum is σ = 176577674. Its totient is φ = 32548800.

The previous prime is 81372089. The next prime is 81372113. The reversal of 81372100 is 127318.

It can be written as a sum of positive squares in 3 ways, for example, as 24127744 + 57244356 = 4912^2 + 7566^2 .

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 5 ways as a sum of consecutive naturals, for example, 406761 + ... + 406960.

Almost surely, 2^81372100 is an apocalyptic number.

It is an amenable number.

81372100 is an abundant number, since it is smaller than the sum of its proper divisors (95205574).

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

81372100 is a wasteful number, since it uses less digits than its factorization.

81372100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813735 (or 813728 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 81372100 is about 9020.6485354436. The cubic root of 81372100 is about 433.3364036600.

Adding to 81372100 its reverse (127318), we get a palindrome (81499418).

It can be divided in two parts, 81 and 372100, that multiplied together give a square (30140100 = 5490²).

The spelling of 81372100 in words is "eighty-one million, three hundred seventy-two thousand, one hundred".