21150816 has 48 divisors (see below), whose sum is σ = 56582064. Its totient is φ = 6915584.

The previous prime is 21150809. The next prime is 21150817. The reversal of 21150816 is 61805112.

It is a tau number, because it is divible by the number of its divisors (48).

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 (21150817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3010 + ... + 7166.

It is an arithmetic number, because the mean of its divisors is an integer number (1178793).

Almost surely, 2^21150816 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 21150816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28291032).

21150816 is an abundant number, since it is smaller than the sum of its proper divisors (35431248).

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

21150816 is a wasteful number, since it uses less digits than its factorization.

21150816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4223 (or 4215 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 21150816 is about 4599.0016307890. The cubic root of 21150816 is about 276.5513030099.

Adding to 21150816 its reverse (61805112), we get a palindrome (82955928).

The spelling of 21150816 in words is "twenty-one million, one hundred fifty thousand, eight hundred sixteen".