85991021 has 2 divisors, whose sum is σ = 85991022. Its totient is φ = 85991020.

The previous prime is 85990991. The next prime is 85991039. The reversal of 85991021 is 12019958.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45414121 + 40576900 = 6739^2 + 6370^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-85991021 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (85991041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42995510 + 42995511.

It is an arithmetic number, because the mean of its divisors is an integer number (42995511).

Almost surely, 2^85991021 is an apocalyptic number.

It is an amenable number.

85991021 is a deficient number, since it is larger than the sum of its proper divisors (1).

85991021 is an equidigital number, since it uses as much as digits as its factorization.

85991021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 35.

The square root of 85991021 is about 9273.1343676235. The cubic root of 85991021 is about 441.3851339458.

The spelling of 85991021 in words is "eighty-five million, nine hundred ninety-one thousand, twenty-one".