78421705 has 4 divisors (see below), whose sum is σ = 94106052. Its totient is φ = 62737360.

The previous prime is 78421669. The next prime is 78421757. The reversal of 78421705 is 50712487.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9066121 + 69355584 = 3011^2 + 8328^2 .

It is not a de Polignac number, because 78421705 - 2²¹ = 76324553 is a prime.

It is a super-2 number, since 2×78421705² = 12299927630214050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7842166 + ... + 7842175.

It is an arithmetic number, because the mean of its divisors is an integer number (23526513).

Almost surely, 2^78421705 is an apocalyptic number.

It is an amenable number.

78421705 is a deficient number, since it is larger than the sum of its proper divisors (15684347).

78421705 is a wasteful number, since it uses less digits than its factorization.

78421705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15684346.

The product of its (nonzero) digits is 15680, while the sum is 34.

The square root of 78421705 is about 8855.6030285916. The cubic root of 78421705 is about 428.0344853135.

The spelling of 78421705 in words is "seventy-eight million, four hundred twenty-one thousand, seven hundred five".