20968981 has 4 divisors (see below), whose sum is σ = 22875264. Its totient is φ = 19062700.

The previous prime is 20968979. The next prime is 20969009. The reversal of 20968981 is 18986902.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20968981 - 2¹ = 20968979 is a prime.

It is a super-2 number, since 2×20968981² = 879396328356722, 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 (20968901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 953125 + ... + 953146.

It is an arithmetic number, because the mean of its divisors is an integer number (5718816).

Almost surely, 2^20968981 is an apocalyptic number.

It is an amenable number.

20968981 is a deficient number, since it is larger than the sum of its proper divisors (1906283).

20968981 is a wasteful number, since it uses less digits than its factorization.

20968981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1906282.

The product of its (nonzero) digits is 62208, while the sum is 43.

The square root of 20968981 is about 4579.1899938745. The cubic root of 20968981 is about 275.7565109083.

The spelling of 20968981 in words is "twenty million, nine hundred sixty-eight thousand, nine hundred eighty-one".