21501340 has 48 divisors (see below), whose sum is σ = 52113600. Its totient is φ = 7299072.

The previous prime is 21501323. The next prime is 21501349. The reversal of 21501340 is 4310512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21501349) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14556 + ... + 15964.

It is an arithmetic number, because the mean of its divisors is an integer number (1085700).

Almost surely, 2^21501340 is an apocalyptic number.

21501340 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 21501340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26056800).

21501340 is an abundant number, since it is smaller than the sum of its proper divisors (30612260).

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

21501340 is a wasteful number, since it uses less digits than its factorization.

21501340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1534 (or 1532 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21501340 is about 4636.9537414126. The cubic root of 21501340 is about 278.0706650580.

Adding to 21501340 its reverse (4310512), we get a palindrome (25811852).

The spelling of 21501340 in words is "twenty-one million, five hundred one thousand, three hundred forty".