84247981 has 2 divisors, whose sum is σ = 84247982. Its totient is φ = 84247980.

The previous prime is 84247979. The next prime is 84247991. The reversal of 84247981 is 18974248.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67158025 + 17089956 = 8195^2 + 4134^2 .

It is a cyclic number.

It is not a de Polignac number, because 84247981 - 2¹ = 84247979 is a prime.

It is a super-2 number, since 2×84247981² = 14195444605152722, which contains 22 as substring.

Together with 84247979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84247901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42123990 + 42123991.

It is an arithmetic number, because the mean of its divisors is an integer number (42123991).

Almost surely, 2^84247981 is an apocalyptic number.

It is an amenable number.

84247981 is a deficient number, since it is larger than the sum of its proper divisors (1).

84247981 is an equidigital number, since it uses as much as digits as its factorization.

84247981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129024, while the sum is 43.

The square root of 84247981 is about 9178.6698927459. The cubic root of 84247981 is about 438.3824578651.

The spelling of 84247981 in words is "eighty-four million, two hundred forty-seven thousand, nine hundred eighty-one".