72340781 has 2 divisors, whose sum is σ = 72340782. Its totient is φ = 72340780.

The previous prime is 72340691. The next prime is 72340783. The reversal of 72340781 is 18704327.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68475625 + 3865156 = 8275^2 + 1966^2 .

It is an emirp because it is prime and its reverse (18704327) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72340781 - 2²⁶ = 5231917 is a prime.

It is a super-2 number, since 2×72340781² = 10466377191379922, which contains 22 as substring.

Together with 72340783, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_4247663 and since 72340781 and 4247663 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72340783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36170390 + 36170391.

It is an arithmetic number, because the mean of its divisors is an integer number (36170391).

Almost surely, 2^72340781 is an apocalyptic number.

It is an amenable number.

72340781 is a deficient number, since it is larger than the sum of its proper divisors (1).

72340781 is an equidigital number, since it uses as much as digits as its factorization.

72340781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9408, while the sum is 32.

The square root of 72340781 is about 8505.3383824513. The cubic root of 72340781 is about 416.6720772275.

The spelling of 72340781 in words is "seventy-two million, three hundred forty thousand, seven hundred eighty-one".