21905016 has 64 divisors (see below), whose sum is σ = 65318400. Its totient is φ = 5985408.

The previous prime is 21905011. The next prime is 21905053. The reversal of 21905016 is 61050912.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21905011) 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, 1030 + ... + 6698.

It is an arithmetic number, because the mean of its divisors is an integer number (1020600).

Almost surely, 2^21905016 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 21905016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32659200).

21905016 is an abundant number, since it is smaller than the sum of its proper divisors (43413384).

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

21905016 is a wasteful number, since it uses less digits than its factorization.

21905016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5708 (or 5704 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 24.

The square root of 21905016 is about 4680.2794788346. The cubic root of 21905016 is about 279.8000954083.

Adding to 21905016 its reverse (61050912), we get a palindrome (82955928).

The spelling of 21905016 in words is "twenty-one million, nine hundred five thousand, sixteen".