16821420 has 144 divisors (see below), whose sum is σ = 59345664. Its totient is φ = 3484800.

The previous prime is 16821407. The next prime is 16821433. The reversal of 16821420 is 2412861.

It is an interprime number because it is at equal distance from previous prime (16821407) and next prime (16821433).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 50655 + ... + 50985.

Almost surely, 2^16821420 is an apocalyptic number.

16821420 is a gapful number since it is divisible by the number (10) 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 16821420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29672832).

16821420 is an abundant number, since it is smaller than the sum of its proper divisors (42524244).

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

16821420 is a wasteful number, since it uses less digits than its factorization.

16821420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372 (or 359 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 16821420 is about 4101.3924464747. The cubic root of 16821420 is about 256.2246359983.

The spelling of 16821420 in words is "sixteen million, eight hundred twenty-one thousand, four hundred twenty".