21938964 has 48 divisors (see below), whose sum is σ = 55278720. Its totient is φ = 6751360.

The previous prime is 21938951. The next prime is 21938971. The reversal of 21938964 is 46983912.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 6634 + ... + 9374.

It is an arithmetic number, because the mean of its divisors is an integer number (1151640).

Almost surely, 2^21938964 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 21938964, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27639360).

21938964 is an abundant number, since it is smaller than the sum of its proper divisors (33339756).

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

21938964 is a wasteful number, since it uses less digits than its factorization.

21938964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2800 (or 2798 counting only the distinct ones).

The product of its digits is 93312, while the sum is 42.

The square root of 21938964 is about 4683.9047812696. The cubic root of 21938964 is about 279.9445638551.

It can be divided in two parts, 219389 and 64, that added together give a triangular number (219453 = T₆₆₂).

The spelling of 21938964 in words is "twenty-one million, nine hundred thirty-eight thousand, nine hundred sixty-four".