18406778 has 8 divisors (see below), whose sum is σ = 29734068. Its totient is φ = 8495424.

The previous prime is 18406771. The next prime is 18406781. The reversal of 18406778 is 87760481.

It can be written as a sum of positive squares in 2 ways, for example, as 17833729 + 573049 = 4223^2 + 757^2 .

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

It is not an unprimeable number, because it can be changed into a prime (18406771) 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, 353951 + ... + 354002.

Almost surely, 2^18406778 is an apocalyptic number.

18406778 is a deficient number, since it is larger than the sum of its proper divisors (11327290).

18406778 is a wasteful number, since it uses less digits than its factorization.

18406778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 707968.

The product of its (nonzero) digits is 75264, while the sum is 41.

The square root of 18406778 is about 4290.3121098587. The cubic root of 18406778 is about 264.0336370516.

The spelling of 18406778 in words is "eighteen million, four hundred six thousand, seven hundred seventy-eight".