18977981 has 8 divisors (see below), whose sum is σ = 20844000. Its totient is φ = 17135440.

The previous prime is 18977963. The next prime is 18978019.

18977981 is nontrivially palindromic in base 10.

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 18977981 - 2¹⁰ = 18976957 is a prime.

It is a super-2 number, since 2×18977981² = 720327525672722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18977911) 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, 4151 + ... + 7428.

It is an arithmetic number, because the mean of its divisors is an integer number (2605500).

Almost surely, 2^18977981 is an apocalyptic number.

18977981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18977981 is a deficient number, since it is larger than the sum of its proper divisors (1866019).

18977981 is a wasteful number, since it uses less digits than its factorization.

18977981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11739.

The product of its digits is 254016, while the sum is 50.

The square root of 18977981 is about 4356.3724588240. The cubic root of 18977981 is about 266.7370451394.

The spelling of 18977981 in words is "eighteen million, nine hundred seventy-seven thousand, nine hundred eighty-one".