21701440 has 56 divisors (see below), whose sum is σ = 52440840. Its totient is φ = 8552448.

The previous prime is 21701417. The next prime is 21701441. The reversal of 21701440 is 4410712.

It can be written as a sum of positive squares in 4 ways, for example, as 23104 + 21678336 = 152^2 + 4656^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21701441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22896 + ... + 23824.

Almost surely, 2^21701440 is an apocalyptic number.

21701440 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 21701440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26220420).

21701440 is an abundant number, since it is smaller than the sum of its proper divisors (30739400).

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

21701440 is an equidigital number, since it uses as much as digits as its factorization.

21701440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1019 (or 1009 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 21701440 is about 4658.4804389414. The cubic root of 21701440 is about 278.9306148464.

The spelling of 21701440 in words is "twenty-one million, seven hundred one thousand, four hundred forty".