21953764 has 36 divisors (see below), whose sum is σ = 45174780. Its totient is φ = 9307200.

The previous prime is 21953741. The next prime is 21953777. The reversal of 21953764 is 46735912.

It can be written as a sum of positive squares in 2 ways, for example, as 10188864 + 11764900 = 3192^2 + 3430^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19242 + ... + 20350.

It is an arithmetic number, because the mean of its divisors is an integer number (1254855).

Almost surely, 2^21953764 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21953764, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22587390).

21953764 is an abundant number, since it is smaller than the sum of its proper divisors (23221016).

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

21953764 is a wasteful number, since it uses less digits than its factorization.

21953764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1228 (or 1219 counting only the distinct ones).

The product of its digits is 45360, while the sum is 37.

The square root of 21953764 is about 4685.4843933152. The cubic root of 21953764 is about 280.0074997991.

The spelling of 21953764 in words is "twenty-one million, nine hundred fifty-three thousand, seven hundred sixty-four".