18699681 has 48 divisors (see below), whose sum is σ = 33730560. Its totient is φ = 8948160.

The previous prime is 18699647. The next prime is 18699683.

18699681 = 158² + 159² + ... + 391².

18699681 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 18699681 - 2¹¹ = 18697633 is a prime.

It is a super-2 number, since 2×18699681² = 699356139003522, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18699681.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18699683) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 38800 + ... + 39278.

It is an arithmetic number, because the mean of its divisors is an integer number (702720).

Almost surely, 2^18699681 is an apocalyptic number.

18699681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18699681 is a deficient number, since it is larger than the sum of its proper divisors (15030879).

18699681 is a wasteful number, since it uses less digits than its factorization.

18699681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526 (or 513 counting only the distinct ones).

The product of its digits is 186624, while the sum is 48.

The square root of 18699681 is about 4324.3127777717. The cubic root of 18699681 is about 265.4267764209.

The spelling of 18699681 in words is "eighteen million, six hundred ninety-nine thousand, six hundred eighty-one".