78724913 has 4 divisors (see below), whose sum is σ = 78791028. Its totient is φ = 78658800.

The previous prime is 78724897. The next prime is 78724951. The reversal of 78724913 is 31942787.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31942787 = 257 ⋅124291.

It can be written as a sum of positive squares in 2 ways, for example, as 32171584 + 46553329 = 5672^2 + 6823^2 .

It is a cyclic number.

It is not a de Polignac number, because 78724913 - 2⁴ = 78724897 is a prime.

It is a super-2 number, since 2×78724913² = 12395223853715138, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78724963) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31238 + ... + 33663.

It is an arithmetic number, because the mean of its divisors is an integer number (19697757).

Almost surely, 2^78724913 is an apocalyptic number.

It is an amenable number.

78724913 is a deficient number, since it is larger than the sum of its proper divisors (66115).

78724913 is a wasteful number, since it uses less digits than its factorization.

78724913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66114.

The product of its digits is 84672, while the sum is 41.

The square root of 78724913 is about 8872.7060697399. The cubic root of 78724913 is about 428.5854236647.

The spelling of 78724913 in words is "seventy-eight million, seven hundred twenty-four thousand, nine hundred thirteen".