866620820 has 48 divisors (see below), whose sum is σ = 1978276608. Its totient is φ = 316982400.

The previous prime is 866620801. The next prime is 866620879. The reversal of 866620820 is 28026668.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12245 + ... + 43395.

It is an arithmetic number, because the mean of its divisors is an integer number (41214096).

Almost surely, 2^866620820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 866620820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (989138304).

866620820 is an abundant number, since it is smaller than the sum of its proper divisors (1111655788).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

866620820 is a wasteful number, since it uses less digits than its factorization.

866620820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31280 (or 31278 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 38.

The square root of 866620820 is about 29438.4242105450. The cubic root of 866620820 is about 953.4026897341.

The spelling of 866620820 in words is "eight hundred sixty-six million, six hundred twenty thousand, eight hundred twenty".