84391921 has 2 divisors, whose sum is σ = 84391922. Its totient is φ = 84391920.

The previous prime is 84391919. The next prime is 84391933. The reversal of 84391921 is 12919348.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55651600 + 28740321 = 7460^2 + 5361^2 .

It is a cyclic number.

It is not a de Polignac number, because 84391921 - 2¹ = 84391919 is a prime.

Together with 84391919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (84311921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42195960 + 42195961.

It is an arithmetic number, because the mean of its divisors is an integer number (42195961).

Almost surely, 2^84391921 is an apocalyptic number.

It is an amenable number.

84391921 is a deficient number, since it is larger than the sum of its proper divisors (1).

84391921 is an equidigital number, since it uses as much as digits as its factorization.

84391921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 37.

The square root of 84391921 is about 9186.5075518393. The cubic root of 84391921 is about 438.6319786561.

The spelling of 84391921 in words is "eighty-four million, three hundred ninety-one thousand, nine hundred twenty-one".