81630278 has 4 divisors (see below), whose sum is σ = 122445420. Its totient is φ = 40815138.

The previous prime is 81630257. The next prime is 81630287. The reversal of 81630278 is 87203618.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20407568 + ... + 20407571.

It is an arithmetic number, because the mean of its divisors is an integer number (30611355).

Almost surely, 2^81630278 is an apocalyptic number.

81630278 is a deficient number, since it is larger than the sum of its proper divisors (40815142).

81630278 is a wasteful number, since it uses less digits than its factorization.

81630278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40815141.

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 81630278 is about 9034.9475925431. The cubic root of 81630278 is about 433.7942174634.

The spelling of 81630278 in words is "eighty-one million, six hundred thirty thousand, two hundred seventy-eight".