18681691 has 24 divisors (see below), whose sum is σ = 23614416. Its totient is φ = 14676480.

The previous prime is 18681671. The next prime is 18681697. The reversal of 18681691 is 19618681.

It is not a de Polignac number, because 18681691 - 2¹¹ = 18679643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18681697) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33880 + ... + 34426.

It is an arithmetic number, because the mean of its divisors is an integer number (983934).

Almost surely, 2^18681691 is an apocalyptic number.

18681691 is a deficient number, since it is larger than the sum of its proper divisors (4932725).

18681691 is a wasteful number, since it uses less digits than its factorization.

18681691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 619 (or 612 counting only the distinct ones).

The product of its digits is 20736, while the sum is 40.

The square root of 18681691 is about 4322.2321779377. The cubic root of 18681691 is about 265.3416313000.

The spelling of 18681691 in words is "eighteen million, six hundred eighty-one thousand, six hundred ninety-one".