81630291 has 4 divisors (see below), whose sum is σ = 108840392. Its totient is φ = 54420192.

The previous prime is 81630287. The next prime is 81630293. The reversal of 81630291 is 19203618.

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

It is not a de Polignac number, because 81630291 - 2² = 81630287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81630293) 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, 13605046 + ... + 13605051.

It is an arithmetic number, because the mean of its divisors is an integer number (27210098).

Almost surely, 2^81630291 is an apocalyptic number.

81630291 is a deficient number, since it is larger than the sum of its proper divisors (27210101).

81630291 is a wasteful number, since it uses less digits than its factorization.

81630291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27210100.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 81630291 is about 9034.9483119717. The cubic root of 81630291 is about 433.7942404914.

The spelling of 81630291 in words is "eighty-one million, six hundred thirty thousand, two hundred ninety-one".