21446820 has 72 divisors (see below), whose sum is σ = 68490240. Its totient is φ = 5417280.

The previous prime is 21446819. The next prime is 21446837. The reversal of 21446820 is 2864412.

It is a super-2 number, since 2×21446820² = 919932176224800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 285 + ... + 6555.

Almost surely, 2^21446820 is an apocalyptic number.

21446820 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 21446820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34245120).

21446820 is an abundant number, since it is smaller than the sum of its proper divisors (47043420).

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

21446820 is a wasteful number, since it uses less digits than its factorization.

21446820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6305 (or 6300 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 21446820 is about 4631.0711503927. The cubic root of 21446820 is about 277.8354356164.

The spelling of 21446820 in words is "twenty-one million, four hundred forty-six thousand, eight hundred twenty".