78390890 has 8 divisors (see below), whose sum is σ = 141103620. Its totient is φ = 31356352.

The previous prime is 78390889. The next prime is 78390899. The reversal of 78390890 is 9809387.

It can be written as a sum of positive squares in 2 ways, for example, as 72403081 + 5987809 = 8509^2 + 2447^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×78390890² = 12290263269984200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78390899) 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, 3919535 + ... + 3919554.

Almost surely, 2^78390890 is an apocalyptic number.

78390890 is a deficient number, since it is larger than the sum of its proper divisors (62712730).

78390890 is a wasteful number, since it uses less digits than its factorization.

78390890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7839096.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 78390890 is about 8853.8629987142. The cubic root of 78390890 is about 427.9784140568.

The spelling of 78390890 in words is "seventy-eight million, three hundred ninety thousand, eight hundred ninety".