84870991 has 2 divisors, whose sum is σ = 84870992. Its totient is φ = 84870990.

The previous prime is 84870979. The next prime is 84871001. The reversal of 84870991 is 19907848.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 84870991 - 2⁵ = 84870959 is a prime.

It is a super-2 number, since 2×84870991² = 14406170226644162, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84870911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42435495 + 42435496.

It is an arithmetic number, because the mean of its divisors is an integer number (42435496).

Almost surely, 2^84870991 is an apocalyptic number.

84870991 is a deficient number, since it is larger than the sum of its proper divisors (1).

84870991 is an equidigital number, since it uses as much as digits as its factorization.

84870991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 46.

The square root of 84870991 is about 9212.5453051803. The cubic root of 84870991 is about 439.4604112106.

The spelling of 84870991 in words is "eighty-four million, eight hundred seventy thousand, nine hundred ninety-one".