81155066 has 4 divisors (see below), whose sum is σ = 121732602. Its totient is φ = 40577532.

The previous prime is 81155057. The next prime is 81155119. The reversal of 81155066 is 66055118.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66055118 = 2 ⋅33027559.

It can be written as a sum of positive squares in only one way, i.e., 79727041 + 1428025 = 8929^2 + 1195^2 .

It is a super-2 number, since 2×81155066² = 13172289474928712, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20288765 + ... + 20288768.

Almost surely, 2^81155066 is an apocalyptic number.

81155066 is a deficient number, since it is larger than the sum of its proper divisors (40577536).

81155066 is a wasteful number, since it uses less digits than its factorization.

81155066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40577535.

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 81155066 is about 9008.6106586976. The cubic root of 81155066 is about 432.9507986345.

The spelling of 81155066 in words is "eighty-one million, one hundred fifty-five thousand, sixty-six".