21151680 has 112 divisors (see below), whose sum is σ = 73298304. Its totient is φ = 5125120.

The previous prime is 21151673. The next prime is 21151687. The reversal of 21151680 is 8615112.

It is an interprime number because it is at equal distance from previous prime (21151673) and next prime (21151687).

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

It is a zygodrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 21151680.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21151687) 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, 9559 + ... + 11561.

Almost surely, 2^21151680 is an apocalyptic number.

21151680 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 21151680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36649152).

21151680 is an abundant number, since it is smaller than the sum of its proper divisors (52146624).

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

21151680 is a wasteful number, since it uses less digits than its factorization.

21151680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2034 (or 2024 counting only the distinct ones).

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

The square root of 21151680 is about 4599.0955632602. The cubic root of 21151680 is about 276.5550686183. Note that the first 3 decimals are identical.

Adding to 21151680 its reverse (8615112), we get a palindrome (29766792).

The spelling of 21151680 in words is "twenty-one million, one hundred fifty-one thousand, six hundred eighty".