21073640 has 64 divisors (see below), whose sum is σ = 54984960. Its totient is φ = 7119360.

The previous prime is 21073627. The next prime is 21073643. The reversal of 21073640 is 4637012.

It is a super-3 number, since 3×21073640³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21073643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19925 + ... + 20955.

It is an arithmetic number, because the mean of its divisors is an integer number (859140).

Almost surely, 2^21073640 is an apocalyptic number.

21073640 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 21073640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27492480).

21073640 is an abundant number, since it is smaller than the sum of its proper divisors (33911320).

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

21073640 is a wasteful number, since it uses less digits than its factorization.

21073640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1122 (or 1118 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 21073640 is about 4590.6034461713. The cubic root of 21073640 is about 276.2145290001.

The spelling of 21073640 in words is "twenty-one million, seventy-three thousand, six hundred forty".