42771721 has 2 divisors, whose sum is σ = 42771722. Its totient is φ = 42771720.

The previous prime is 42771719. The next prime is 42771731. The reversal of 42771721 is 12717724.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42771600 + 121 = 6540^2 + 11^2 .

It is a cyclic number.

It is not a de Polignac number, because 42771721 - 2¹ = 42771719 is a prime.

Together with 42771719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (42771731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21385860 + 21385861.

It is an arithmetic number, because the mean of its divisors is an integer number (21385861).

Almost surely, 2^42771721 is an apocalyptic number.

It is an amenable number.

42771721 is a deficient number, since it is larger than the sum of its proper divisors (1).

42771721 is an equidigital number, since it uses as much as digits as its factorization.

42771721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5488, while the sum is 31.

The square root of 42771721 is about 6540.0092507580. The cubic root of 42771721 is about 349.7187427519.

The spelling of 42771721 in words is "forty-two million, seven hundred seventy-one thousand, seven hundred twenty-one".