81261457 has 2 divisors, whose sum is σ = 81261458. Its totient is φ = 81261456.

The previous prime is 81261437. The next prime is 81261487. The reversal of 81261457 is 75416218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70963776 + 10297681 = 8424^2 + 3209^2 .

It is a cyclic number.

It is not a de Polignac number, because 81261457 - 2⁷ = 81261329 is a prime.

It is not a weakly prime, because it can be changed into another prime (81261437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40630728 + 40630729.

It is an arithmetic number, because the mean of its divisors is an integer number (40630729).

Almost surely, 2^81261457 is an apocalyptic number.

It is an amenable number.

81261457 is a deficient number, since it is larger than the sum of its proper divisors (1).

81261457 is an equidigital number, since it uses as much as digits as its factorization.

81261457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13440, while the sum is 34.

The square root of 81261457 is about 9014.5136862728. The cubic root of 81261457 is about 433.1399096653.

It can be divided in two parts, 81261 and 457, that added together give a palindrome (81718).

The spelling of 81261457 in words is "eighty-one million, two hundred sixty-one thousand, four hundred fifty-seven".