857439706021 has 2 divisors, whose sum is σ = 857439706022. Its totient is φ = 857439706020.

The previous prime is 857439705973. The next prime is 857439706043. The reversal of 857439706021 is 120607934758.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 565962813025 + 291476892996 = 752305^2 + 539886^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-857439706021 is a prime.

It is a super-2 number, since 2×857439706021² (a number of 25 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 857439706021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857439746021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428719853010 + 428719853011.

It is an arithmetic number, because the mean of its divisors is an integer number (428719853011).

It is a 1-persistent number, because it is pandigital, but 2⋅857439706021 = 1714879412042 is not.

Almost surely, 2^857439706021 is an apocalyptic number.

It is an amenable number.

857439706021 is a deficient number, since it is larger than the sum of its proper divisors (1).

857439706021 is an equidigital number, since it uses as much as digits as its factorization.

857439706021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2540160, while the sum is 52.

The spelling of 857439706021 in words is "eight hundred fifty-seven billion, four hundred thirty-nine million, seven hundred six thousand, twenty-one".