866051821 has 12 divisors (see below), whose sum is σ = 909751360. Its totient is φ = 824365080.

The previous prime is 866051803. The next prime is 866051827. The reversal of 866051821 is 128150668.

It is not a de Polignac number, because 866051821 - 2¹⁵ = 866019053 is a prime.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866051827) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 107740 + ... + 115498.

Almost surely, 2^866051821 is an apocalyptic number.

It is an amenable number.

866051821 is a deficient number, since it is larger than the sum of its proper divisors (43699539).

866051821 is a wasteful number, since it uses less digits than its factorization.

866051821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8016 (or 7993 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 866051821 is about 29428.7584005850. The cubic root of 866051821 is about 953.1939848677.

The spelling of 866051821 in words is "eight hundred sixty-six million, fifty-one thousand, eight hundred twenty-one".