78390545 has 4 divisors (see below), whose sum is σ = 94068660. Its totient is φ = 62712432.

The previous prime is 78390541. The next prime is 78390547. The reversal of 78390545 is 54509387.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54509387 = 53 ⋅1028479.

It can be written as a sum of positive squares in 2 ways, for example, as 53699584 + 24690961 = 7328^2 + 4969^2 .

It is a cyclic number.

It is not a de Polignac number, because 78390545 - 2² = 78390541 is a prime.

It is a super-2 number, since 2×78390545² = 12290155090794050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78390541) 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, 7839050 + ... + 7839059.

It is an arithmetic number, because the mean of its divisors is an integer number (23517165).

Almost surely, 2^78390545 is an apocalyptic number.

It is an amenable number.

78390545 is a deficient number, since it is larger than the sum of its proper divisors (15678115).

78390545 is a wasteful number, since it uses less digits than its factorization.

78390545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15678114.

The product of its (nonzero) digits is 151200, while the sum is 41.

The square root of 78390545 is about 8853.8435156716. The cubic root of 78390545 is about 427.9777862084.

The spelling of 78390545 in words is "seventy-eight million, three hundred ninety thousand, five hundred forty-five".