81993026 has 8 divisors (see below), whose sum is σ = 124078284. Its totient is φ = 40633600.

The previous prime is 81993017. The next prime is 81993029. The reversal of 81993026 is 62039918.

It is a Cunningham number, because it is equal to 9055²+1.

It can be written as a sum of positive squares in 2 ways, for example, as 81993025 + 1 = 9055^2 + 1^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81993029) 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, 181175 + ... + 181626.

Almost surely, 2^81993026 is an apocalyptic number.

81993026 is a deficient number, since it is larger than the sum of its proper divisors (42085258).

81993026 is a wasteful number, since it uses less digits than its factorization.

81993026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362916.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 81993026 is about 9055.0000552181. Note that the first 4 decimals coincide. The cubic root of 81993026 is about 434.4358317993.

The spelling of 81993026 in words is "eighty-one million, nine hundred ninety-three thousand, twenty-six".