21073920 has 208 divisors, whose sum is σ = 78633600. Its totient is φ = 4816896.

The previous prime is 21073919. The next prime is 21073933. The reversal of 21073920 is 2937012.

It is a super-2 number, since 2×21073920² = 888220208332800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3010557 + ... + 3010563.

Almost surely, 2^21073920 is an apocalyptic number.

21073920 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 21073920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39316800).

21073920 is an abundant number, since it is smaller than the sum of its proper divisors (57559680).

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

21073920 is an frugal number, since it uses more digits than its factorization.

21073920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53 (or 17 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 24.

The square root of 21073920 is about 4590.6339431499. The cubic root of 21073920 is about 276.2157523250.

The spelling of 21073920 in words is "twenty-one million, seventy-three thousand, nine hundred twenty".