1020866399 has 4 divisors (see below), whose sum is σ = 1166704464. Its totient is φ = 875028336.

The previous prime is 1020866393. The next prime is 1020866419. The reversal of 1020866399 is 9936680201.

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

It is not a de Polignac number, because 1020866399 - 2¹² = 1020862303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1020866393) 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, 72919022 + ... + 72919035.

It is an arithmetic number, because the mean of its divisors is an integer number (291676116).

Almost surely, 2^1020866399 is an apocalyptic number.

1020866399 is a deficient number, since it is larger than the sum of its proper divisors (145838065).

1020866399 is an equidigital number, since it uses as much as digits as its factorization.

1020866399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145838064.

The product of its (nonzero) digits is 139968, while the sum is 44.

The square root of 1020866399 is about 31950.9999687021. Note that the first 4 decimals coincide. The cubic root of 1020866399 is about 1006.9076409625.

The spelling of 1020866399 in words is "one billion, twenty million, eight hundred sixty-six thousand, three hundred ninety-nine".