21356880 has 160 divisors (see below), whose sum is σ = 71352576. Its totient is φ = 5271552.

The previous prime is 21356873. The next prime is 21356891. The reversal of 21356880 is 8865312.

It is a happy number.

It is a super-2 number, since 2×21356880² = 912232646668800, which contains 22 as substring.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 292524 + ... + 292596.

Almost surely, 2^21356880 is an apocalyptic number.

21356880 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 21356880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35676288).

21356880 is an abundant number, since it is smaller than the sum of its proper divisors (49995696).

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

21356880 is a wasteful number, since it uses less digits than its factorization.

21356880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165 (or 159 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 21356880 is about 4621.3504519783. The cubic root of 21356880 is about 277.4465118887.

The spelling of 21356880 in words is "twenty-one million, three hundred fifty-six thousand, eight hundred eighty".