21152340 has 120 divisors (see below), whose sum is σ = 72448992. Its totient is φ = 5123520.

The previous prime is 21152333. The next prime is 21152381. The reversal of 21152340 is 4325112.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 17227 + ... + 18413.

Almost surely, 2^21152340 is an apocalyptic number.

21152340 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 21152340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36224496).

21152340 is an abundant number, since it is smaller than the sum of its proper divisors (51296652).

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

21152340 is a wasteful number, since it uses less digits than its factorization.

21152340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1219 (or 1208 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21152340 is about 4599.1673159388. The cubic root of 21152340 is about 276.5579450557.

Adding to 21152340 its reverse (4325112), we get a palindrome (25477452).

The spelling of 21152340 in words is "twenty-one million, one hundred fifty-two thousand, three hundred forty".