21310740 has 144 divisors (see below), whose sum is σ = 72334080. Its totient is φ = 5034240.

The previous prime is 21310739. The next prime is 21310747. The reversal of 21310740 is 4701312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310747) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 92946 + ... + 93174.

It is an arithmetic number, because the mean of its divisors is an integer number (502320).

Almost surely, 2^21310740 is an apocalyptic number.

21310740 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 21310740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36167040).

21310740 is an abundant number, since it is smaller than the sum of its proper divisors (51023340).

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

21310740 is a wasteful number, since it uses less digits than its factorization.

21310740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302 (or 297 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21310740 is about 4616.3557055322. The cubic root of 21310740 is about 277.2465667663.

The spelling of 21310740 in words is "twenty-one million, three hundred ten thousand, seven hundred forty".