21968766 has 32 divisors (see below), whose sum is σ = 49497120. Its totient is φ = 7221312.

The previous prime is 21968761. The next prime is 21968773. The reversal of 21968766 is 66786912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21968761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1156 + ... + 6728.

It is an arithmetic number, because the mean of its divisors is an integer number (1546785).

Almost surely, 2^21968766 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21968766, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24748560).

21968766 is an abundant number, since it is smaller than the sum of its proper divisors (27528354).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21968766 is a wasteful number, since it uses less digits than its factorization.

21968766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5657 (or 5651 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 21968766 is about 4687.0850216312. The cubic root of 21968766 is about 280.0712658734.

The spelling of 21968766 in words is "twenty-one million, nine hundred sixty-eight thousand, seven hundred sixty-six".