21343640 has 32 divisors (see below), whose sum is σ = 49049280. Its totient is φ = 8355072.

The previous prime is 21343633. The next prime is 21343643. The reversal of 21343640 is 4634312.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21343643) 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, 3797 + ... + 7556.

It is an arithmetic number, because the mean of its divisors is an integer number (1532790).

Almost surely, 2^21343640 is an apocalyptic number.

21343640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21343640 is an abundant number, since it is smaller than the sum of its proper divisors (27705640).

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

21343640 is a wasteful number, since it uses less digits than its factorization.

21343640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11411 (or 11407 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 21343640 is about 4619.9177481856. The cubic root of 21343640 is about 277.3891665715.

Adding to 21343640 its reverse (4634312), we get a palindrome (25977952).

The spelling of 21343640 in words is "twenty-one million, three hundred forty-three thousand, six hundred forty".