869860021 has 2 divisors, whose sum is σ = 869860022. Its totient is φ = 869860020.

The previous prime is 869860007. The next prime is 869860049. The reversal of 869860021 is 120068968.

869860021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 767567025 + 102292996 = 27705^2 + 10114^2 .

It is a cyclic number.

It is not a de Polignac number, because 869860021 - 2¹¹ = 869857973 is a prime.

It is a super-2 number, since 2×869860021² = 1513312912268240882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (869860051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 434930010 + 434930011.

It is an arithmetic number, because the mean of its divisors is an integer number (434930011).

Almost surely, 2^869860021 is an apocalyptic number.

It is an amenable number.

869860021 is a deficient number, since it is larger than the sum of its proper divisors (1).

869860021 is an equidigital number, since it uses as much as digits as its factorization.

869860021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 869860021 is about 29493.3894457724. The cubic root of 869860021 is about 954.5890691130.

The spelling of 869860021 in words is "eight hundred sixty-nine million, eight hundred sixty thousand, twenty-one".