18629981 has 8 divisors (see below), whose sum is σ = 19224504. Its totient is φ = 18040320.

The previous prime is 18629957. The next prime is 18629983. The reversal of 18629981 is 18992681.

It can be written as a sum of positive squares in 4 ways, for example, as 4687225 + 13942756 = 2165^2 + 3734^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18629981 is a prime.

It is a super-2 number, since 2×18629981² = 694152384120722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18629983) 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, 7541 + ... + 9701.

It is an arithmetic number, because the mean of its divisors is an integer number (2403063).

Almost surely, 2^18629981 is an apocalyptic number.

It is an amenable number.

18629981 is a deficient number, since it is larger than the sum of its proper divisors (594523).

18629981 is a wasteful number, since it uses less digits than its factorization.

18629981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2431.

The product of its digits is 62208, while the sum is 44.

The square root of 18629981 is about 4316.2461699954. The cubic root of 18629981 is about 265.0965875515.

The spelling of 18629981 in words is "eighteen million, six hundred twenty-nine thousand, nine hundred eighty-one".