42721181 has 2 divisors, whose sum is σ = 42721182. Its totient is φ = 42721180.

The previous prime is 42721171. The next prime is 42721183. The reversal of 42721181 is 18112724.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41809156 + 912025 = 6466^2 + 955^2 .

It is a cyclic number.

It is not a de Polignac number, because 42721181 - 2⁶ = 42721117 is a prime.

It is a super-2 number, since 2×42721181² = 3650198612069522, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 42721183, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 42721181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42721183) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21360590 + 21360591.

It is an arithmetic number, because the mean of its divisors is an integer number (21360591).

Almost surely, 2^42721181 is an apocalyptic number.

It is an amenable number.

42721181 is a deficient number, since it is larger than the sum of its proper divisors (1).

42721181 is an equidigital number, since it uses as much as digits as its factorization.

42721181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 896, while the sum is 26.

The square root of 42721181 is about 6536.1441997557. The cubic root of 42721181 is about 349.5809433597.

The spelling of 42721181 in words is "forty-two million, seven hundred twenty-one thousand, one hundred eighty-one".