81178783 has 4 divisors (see below), whose sum is σ = 92775760. Its totient is φ = 69581808.

The previous prime is 81178771. The next prime is 81178787. The reversal of 81178783 is 38787118.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81178783 - 2¹³ = 81170591 is a prime.

It is a super-2 number, since 2×81178783² = 13179989618722178, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81178787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5798478 + ... + 5798491.

It is an arithmetic number, because the mean of its divisors is an integer number (23193940).

Almost surely, 2^81178783 is an apocalyptic number.

81178783 is a deficient number, since it is larger than the sum of its proper divisors (11596977).

81178783 is a wasteful number, since it uses less digits than its factorization.

81178783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11596976.

The product of its digits is 75264, while the sum is 43.

The square root of 81178783 is about 9009.9269142430. The cubic root of 81178783 is about 432.9929701401.

It can be divided in two parts, 8117 and 8783, that added together give a square (16900 = 130²).

The spelling of 81178783 in words is "eighty-one million, one hundred seventy-eight thousand, seven hundred eighty-three".