81406249 has 2 divisors, whose sum is σ = 81406250. Its totient is φ = 81406248.

The previous prime is 81406243. The next prime is 81406291. The reversal of 81406249 is 94260418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79780624 + 1625625 = 8932^2 + 1275^2 .

It is a cyclic number.

It is not a de Polignac number, because 81406249 - 2²³ = 73017641 is a prime.

It is not a weakly prime, because it can be changed into another prime (81406243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40703124 + 40703125.

It is an arithmetic number, because the mean of its divisors is an integer number (40703125).

Almost surely, 2^81406249 is an apocalyptic number.

It is an amenable number.

81406249 is a deficient number, since it is larger than the sum of its proper divisors (1).

81406249 is an equidigital number, since it uses as much as digits as its factorization.

81406249 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 81406249 is about 9022.5411608925. The cubic root of 81406249 is about 433.3970138498.

The spelling of 81406249 in words is "eighty-one million, four hundred six thousand, two hundred forty-nine".