840861021 has 144 divisors (see below), whose sum is σ = 1640253888. Its totient is φ = 377395200.

The previous prime is 840861013. The next prime is 840861037. The reversal of 840861021 is 120168048.

840861021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 840861021 - 2³ = 840861013 is a prime.

It is a super-3 number, since 3×840861021³ (a number of 28 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 840861021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (840861221) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 4645551 + ... + 4645731.

It is an arithmetic number, because the mean of its divisors is an integer number (11390652).

Almost surely, 2^840861021 is an apocalyptic number.

It is an amenable number.

840861021 is a deficient number, since it is larger than the sum of its proper divisors (799392867).

840861021 is a wasteful number, since it uses less digits than its factorization.

840861021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252 (or 232 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 840861021 is about 28997.6037113414. The cubic root of 840861021 is about 943.8610695937.

The spelling of 840861021 in words is "eight hundred forty million, eight hundred sixty-one thousand, twenty-one".