71821055691 has 24 divisors (see below), whose sum is σ = 129340084224. Its totient is φ = 37309638960.

The previous prime is 71821055689. The next prime is 71821055783. The reversal of 71821055691 is 19655012817.

71821055691 is a `hidden beast` number, since 7 + 1 + 8 + 2 + 1 + 0 + 556 + 91 = 666.

It is not a de Polignac number, because 71821055691 - 2¹ = 71821055689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (71821055671) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51818251 + ... + 51819636.

It is an arithmetic number, because the mean of its divisors is an integer number (5389170176).

Almost surely, 2^71821055691 is an apocalyptic number.

71821055691 is a deficient number, since it is larger than the sum of its proper divisors (57519028533).

71821055691 is a wasteful number, since it uses less digits than its factorization.

71821055691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103637911 (or 103637908 counting only the distinct ones).

The product of its (nonzero) digits is 151200, while the sum is 45.

The spelling of 71821055691 in words is "seventy-one billion, eight hundred twenty-one million, fifty-five thousand, six hundred ninety-one".