81770291 has 4 divisors (see below), whose sum is σ = 81790152. Its totient is φ = 81750432.

The previous prime is 81770287. The next prime is 81770329. The reversal of 81770291 is 19207718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19207718 = 2 ⋅9603859.

It is a cyclic number.

It is not a de Polignac number, because 81770291 - 2² = 81770287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81770201) 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, 1190 + ... + 12843.

It is an arithmetic number, because the mean of its divisors is an integer number (20447538).

Almost surely, 2^81770291 is an apocalyptic number.

81770291 is a deficient number, since it is larger than the sum of its proper divisors (19861).

81770291 is a wasteful number, since it uses less digits than its factorization.

81770291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19860.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 81770291 is about 9042.6926852570. The cubic root of 81770291 is about 434.0420917361.

The spelling of 81770291 in words is "eighty-one million, seven hundred seventy thousand, two hundred ninety-one".