78273661 has 4 divisors (see below), whose sum is σ = 82878012. Its totient is φ = 73669312.

The previous prime is 78273653. The next prime is 78273683. The reversal of 78273661 is 16637287.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16637287 = 283 ⋅58789.

It can be written as a sum of positive squares in 2 ways, for example, as 40068900 + 38204761 = 6330^2 + 6181^2 .

It is a cyclic number.

It is not a de Polignac number, because 78273661 - 2³ = 78273653 is a prime.

It is a super-2 number, since 2×78273661² = 12253532012685842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78273691) 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, 2302150 + ... + 2302183.

It is an arithmetic number, because the mean of its divisors is an integer number (20719503).

Almost surely, 2^78273661 is an apocalyptic number.

It is an amenable number.

78273661 is a deficient number, since it is larger than the sum of its proper divisors (4604351).

78273661 is a wasteful number, since it uses less digits than its factorization.

78273661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4604350.

The product of its digits is 84672, while the sum is 40.

The square root of 78273661 is about 8847.2403041853. The cubic root of 78273661 is about 427.7649687112.

The spelling of 78273661 in words is "seventy-eight million, two hundred seventy-three thousand, six hundred sixty-one".