84731921 has 2 divisors, whose sum is σ = 84731922. Its totient is φ = 84731920.

The previous prime is 84731891. The next prime is 84731923. The reversal of 84731921 is 12913748.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76807696 + 7924225 = 8764^2 + 2815^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-84731921 is a prime.

Together with 84731923, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_4929083 and since 84731921 and 4929083 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (84731923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42365960 + 42365961.

It is an arithmetic number, because the mean of its divisors is an integer number (42365961).

Almost surely, 2^84731921 is an apocalyptic number.

It is an amenable number.

84731921 is a deficient number, since it is larger than the sum of its proper divisors (1).

84731921 is an equidigital number, since it uses as much as digits as its factorization.

84731921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 84731921 is about 9204.9943508945. The cubic root of 84731921 is about 439.2202460273.

It can be divided in two parts, 847 and 31921, that added together give a 15-th power (32768 = 2¹⁵).

The spelling of 84731921 in words is "eighty-four million, seven hundred thirty-one thousand, nine hundred twenty-one".