18963981 has 6 divisors (see below), whose sum is σ = 27392430. Its totient is φ = 12642648.

The previous prime is 18963979. The next prime is 18964003. The reversal of 18963981 is 18936981.

18963981 is a `hidden beast` number, since 1 + 8 + 9 + 639 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 14516100 + 4447881 = 3810^2 + 2109^2 .

It is not a de Polignac number, because 18963981 - 2¹ = 18963979 is a prime.

It is a super-2 number, since 2×18963981² = 719265150736722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18963911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1053546 + ... + 1053563.

It is an arithmetic number, because the mean of its divisors is an integer number (4565405).

Almost surely, 2^18963981 is an apocalyptic number.

It is an amenable number.

18963981 is a deficient number, since it is larger than the sum of its proper divisors (8428449).

18963981 is a wasteful number, since it uses less digits than its factorization.

18963981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2107115 (or 2107112 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 18963981 is about 4354.7653208870. The cubic root of 18963981 is about 266.6714386299.

Subtracting from 18963981 its reverse (18936981), we obtain a cube (27000 = 30³).

The spelling of 18963981 in words is "eighteen million, nine hundred sixty-three thousand, nine hundred eighty-one".