21671880 has 64 divisors (see below), whose sum is σ = 66139200. Its totient is φ = 5679360.

The previous prime is 21671879. The next prime is 21671891. The reversal of 21671880 is 8817612.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5550 + ... + 8610.

It is an arithmetic number, because the mean of its divisors is an integer number (1033425).

Almost surely, 2^21671880 is an apocalyptic number.

21671880 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 21671880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33069600).

21671880 is an abundant number, since it is smaller than the sum of its proper divisors (44467320).

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

21671880 is a wasteful number, since it uses less digits than its factorization.

21671880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3134 (or 3130 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 33.

The square root of 21671880 is about 4655.3066494056. The cubic root of 21671880 is about 278.8039114961.

The spelling of 21671880 in words is "twenty-one million, six hundred seventy-one thousand, eight hundred eighty".