18691645 has 8 divisors (see below), whose sum is σ = 25634304. Its totient is φ = 12817104.

The previous prime is 18691643. The next prime is 18691657. The reversal of 18691645 is 54619681.

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

It is a cyclic number.

It is not a de Polignac number, because 18691645 - 2¹ = 18691643 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18691598 and 18691607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18691643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 266989 + ... + 267058.

It is an arithmetic number, because the mean of its divisors is an integer number (3204288).

Almost surely, 2^18691645 is an apocalyptic number.

It is an amenable number.

18691645 is a deficient number, since it is larger than the sum of its proper divisors (6942659).

18691645 is an equidigital number, since it uses as much as digits as its factorization.

18691645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534059.

The product of its digits is 51840, while the sum is 40.

The square root of 18691645 is about 4323.3835129445. The cubic root of 18691645 is about 265.3887494765.

Subtracting 18691645 from its reverse (54619681), we obtain a square (35928036 = 5994²).

The spelling of 18691645 in words is "eighteen million, six hundred ninety-one thousand, six hundred forty-five".