81649069 has 2 divisors, whose sum is σ = 81649070. Its totient is φ = 81649068.

The previous prime is 81649021. The next prime is 81649109. The reversal of 81649069 is 96094618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56025225 + 25623844 = 7485^2 + 5062^2 .

It is a cyclic number.

It is not a de Polignac number, because 81649069 - 2¹³ = 81640877 is a prime.

It is a super-2 number, since 2×81649069² = 13333140937133522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81649019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40824534 + 40824535.

It is an arithmetic number, because the mean of its divisors is an integer number (40824535).

Almost surely, 2^81649069 is an apocalyptic number.

It is an amenable number.

81649069 is a deficient number, since it is larger than the sum of its proper divisors (1).

81649069 is an equidigital number, since it uses as much as digits as its factorization.

81649069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 43.

The square root of 81649069 is about 9035.9874391236. The cubic root of 81649069 is about 433.8275008723.

The spelling of 81649069 in words is "eighty-one million, six hundred forty-nine thousand, sixty-nine".