81725122 has 4 divisors (see below), whose sum is σ = 122587686. Its totient is φ = 40862560.

The previous prime is 81725107. The next prime is 81725129. The reversal of 81725122 is 22152718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 50822641 + 30902481 = 7129^2 + 5559^2 .

It is not an unprimeable number, because it can be changed into a prime (81725129) by changing a digit.

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 as a sum of consecutive naturals, namely, 20431279 + ... + 20431282.

Almost surely, 2^81725122 is an apocalyptic number.

81725122 is a deficient number, since it is larger than the sum of its proper divisors (40862564).

81725122 is a wasteful number, since it uses less digits than its factorization.

81725122 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40862563.

The product of its digits is 2240, while the sum is 28.

The square root of 81725122 is about 9040.1947987861. The cubic root of 81725122 is about 433.9621570067.

The spelling of 81725122 in words is "eighty-one million, seven hundred twenty-five thousand, one hundred twenty-two".