80643721 has 2 divisors, whose sum is σ = 80643722. Its totient is φ = 80643720.

The previous prime is 80643697. The next prime is 80643743. The reversal of 80643721 is 12734608.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56250000 + 24393721 = 7500^2 + 4939^2 .

It is a cyclic number.

It is not a de Polignac number, because 80643721 - 2⁹ = 80643209 is a prime.

It is not a weakly prime, because it can be changed into another prime (80643781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40321860 + 40321861.

It is an arithmetic number, because the mean of its divisors is an integer number (40321861).

Almost surely, 2^80643721 is an apocalyptic number.

It is an amenable number.

80643721 is a deficient number, since it is larger than the sum of its proper divisors (1).

80643721 is an equidigital number, since it uses as much as digits as its factorization.

80643721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 80643721 is about 8980.1849090094. The cubic root of 80643721 is about 432.0395643491.

The spelling of 80643721 in words is "eighty million, six hundred forty-three thousand, seven hundred twenty-one".