78262721 has 4 divisors (see below), whose sum is σ = 81665472. Its totient is φ = 74859972.

The previous prime is 78262687. The next prime is 78262739. The reversal of 78262721 is 12726287.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 78262721 - 2²² = 74068417 is a prime.

It is a super-2 number, since 2×78262721² = 12250106996647682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78562721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1701341 + ... + 1701386.

It is an arithmetic number, because the mean of its divisors is an integer number (20416368).

Almost surely, 2^78262721 is an apocalyptic number.

It is an amenable number.

78262721 is a deficient number, since it is larger than the sum of its proper divisors (3402751).

78262721 is a wasteful number, since it uses less digits than its factorization.

78262721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3402750.

The product of its digits is 18816, while the sum is 35.

The square root of 78262721 is about 8846.6220106886. The cubic root of 78262721 is about 427.7450387768.

The spelling of 78262721 in words is "seventy-eight million, two hundred sixty-two thousand, seven hundred twenty-one".