21442340 has 24 divisors (see below), whose sum is σ = 45988992. Its totient is φ = 8394080.

The previous prime is 21442331. The next prime is 21442349. The reversal of 21442340 is 4324412.

It is an interprime number because it is at equal distance from previous prime (21442331) and next prime (21442349).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21442349) 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, 10466 + ... + 12345.

It is an arithmetic number, because the mean of its divisors is an integer number (1916208).

Almost surely, 2^21442340 is an apocalyptic number.

21442340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21442340 is an abundant number, since it is smaller than the sum of its proper divisors (24546652).

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

21442340 is a wasteful number, since it uses less digits than its factorization.

21442340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22867 (or 22865 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21442340 is about 4630.5874357364. The cubic root of 21442340 is about 277.8160887011.

Adding to 21442340 its reverse (4324412), we get a palindrome (25766752).

The spelling of 21442340 in words is "twenty-one million, four hundred forty-two thousand, three hundred forty".