78562721 has 2 divisors, whose sum is σ = 78562722. Its totient is φ = 78562720.

The previous prime is 78562697. The next prime is 78562723. The reversal of 78562721 is 12726587.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57760000 + 20802721 = 7600^2 + 4561^2 .

It is an emirp because it is prime and its reverse (12726587) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78562721 - 2²² = 74368417 is a prime.

It is a super-2 number, since 2×78562721² = 12344202261847682, which contains 22 as substring.

Together with 78562723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78562723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39281360 + 39281361.

It is an arithmetic number, because the mean of its divisors is an integer number (39281361).

Almost surely, 2^78562721 is an apocalyptic number.

It is an amenable number.

78562721 is a deficient number, since it is larger than the sum of its proper divisors (1).

78562721 is an equidigital number, since it uses as much as digits as its factorization.

78562721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 47040, while the sum is 38.

The square root of 78562721 is about 8863.5614173988. The cubic root of 78562721 is about 428.2908920823.

The spelling of 78562721 in words is "seventy-eight million, five hundred sixty-two thousand, seven hundred twenty-one".