21371680 has 48 divisors (see below), whose sum is σ = 55085184. Its totient is φ = 7770880.

The previous prime is 21371663. The next prime is 21371683. The reversal of 21371680 is 8617312.

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21371683) 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, 4312 + ... + 7831.

It is an arithmetic number, because the mean of its divisors is an integer number (1147608).

Almost surely, 2^21371680 is an apocalyptic number.

21371680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21371680 is an abundant number, since it is smaller than the sum of its proper divisors (33713504).

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

21371680 is a wasteful number, since it uses less digits than its factorization.

21371680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12169 (or 12161 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21371680 is about 4622.9514382048. The cubic root of 21371680 is about 277.5105858581.

Adding to 21371680 its reverse (8617312), we get a palindrome (29988992).

The spelling of 21371680 in words is "twenty-one million, three hundred seventy-one thousand, six hundred eighty".