21964540 has 48 divisors (see below), whose sum is σ = 51847488. Its totient is φ = 7755264.

The previous prime is 21964511. The next prime is 21964541. The reversal of 21964540 is 4546912.

It is a super-3 number, since 3×21964540³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21964541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4144 + ... + 7816.

It is an arithmetic number, because the mean of its divisors is an integer number (1080156).

Almost surely, 2^21964540 is an apocalyptic number.

21964540 is a gapful number since it is divisible by the number (20) 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 21964540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25923744).

21964540 is an abundant number, since it is smaller than the sum of its proper divisors (29882948).

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

21964540 is a wasteful number, since it uses less digits than its factorization.

21964540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3718 (or 3716 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 21964540 is about 4686.6341867058. The cubic root of 21964540 is about 280.0533061775.

The spelling of 21964540 in words is "twenty-one million, nine hundred sixty-four thousand, five hundred forty".