81225757 has 2 divisors, whose sum is σ = 81225758. Its totient is φ = 81225756.

The previous prime is 81225737. The next prime is 81225791. The reversal of 81225757 is 75752218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70375321 + 10850436 = 8389^2 + 3294^2 .

It is a cyclic number.

It is not a de Polignac number, because 81225757 - 2¹⁵ = 81192989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81225737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40612878 + 40612879.

It is an arithmetic number, because the mean of its divisors is an integer number (40612879).

Almost surely, 2^81225757 is an apocalyptic number.

It is an amenable number.

81225757 is a deficient number, since it is larger than the sum of its proper divisors (1).

81225757 is an equidigital number, since it uses as much as digits as its factorization.

81225757 is an evil number, because the sum of its binary digits is even.

The product of its digits is 39200, while the sum is 37.

The square root of 81225757 is about 9012.5333286485. The cubic root of 81225757 is about 433.0764709810.

It can be divided in two parts, 812 and 25757, that added together give a square (26569 = 163²).

The spelling of 81225757 in words is "eighty-one million, two hundred twenty-five thousand, seven hundred fifty-seven".