81628457 has 2 divisors, whose sum is σ = 81628458. Its totient is φ = 81628456.

The previous prime is 81628429. The next prime is 81628513. The reversal of 81628457 is 75482618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81198121 + 430336 = 9011^2 + 656^2 .

It is a cyclic number.

It is not a de Polignac number, because 81628457 - 2⁸ = 81628201 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81625457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40814228 + 40814229.

It is an arithmetic number, because the mean of its divisors is an integer number (40814229).

Almost surely, 2^81628457 is an apocalyptic number.

It is an amenable number.

81628457 is a deficient number, since it is larger than the sum of its proper divisors (1).

81628457 is an equidigital number, since it uses as much as digits as its factorization.

81628457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 107520, while the sum is 41.

The square root of 81628457 is about 9034.8468166317. The cubic root of 81628457 is about 433.7909917603.

The spelling of 81628457 in words is "eighty-one million, six hundred twenty-eight thousand, four hundred fifty-seven".