21965904 has 100 divisors (see below), whose sum is σ = 67382964. Its totient is φ = 6884352.

The previous prime is 21965899. The next prime is 21965927. The reversal of 21965904 is 40956912.

It can be written as a sum of positive squares in 2 ways, for example, as 18045504 + 3920400 = 4248^2 + 1980^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a zygodrome in base 11.

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 19 ways as a sum of consecutive naturals, for example, 21534 + ... + 22530.

Almost surely, 2^21965904 is an apocalyptic number.

21965904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21965904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33691482).

21965904 is an abundant number, since it is smaller than the sum of its proper divisors (45417060).

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

21965904 is a wasteful number, since it uses less digits than its factorization.

21965904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1034 (or 1019 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 21965904 is about 4686.7797046586. The cubic root of 21965904 is about 280.0591031697.

It can be divided in two parts, 2196 and 5904, that added together give a square (8100 = 90²).

The spelling of 21965904 in words is "twenty-one million, nine hundred sixty-five thousand, nine hundred four".