21140442 has 12 divisors (see below), whose sum is σ = 45804330. Its totient is φ = 7046808.

The previous prime is 21140423. The next prime is 21140501. The reversal of 21140442 is 24404112.

It can be written as a sum of positive squares in only one way, i.e., 16818201 + 4322241 = 4101^2 + 2079^2 .

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1174469 = 21140442 / (2 + 1 + 1 + 4 + 0 + 4 + 4 + 2).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 587217 + ... + 587252.

Almost surely, 2^21140442 is an apocalyptic number.

21140442 is an abundant number, since it is smaller than the sum of its proper divisors (24663888).

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

21140442 is a wasteful number, since it uses less digits than its factorization.

21140442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1174477 (or 1174474 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 21140442 is about 4597.8736389770. The cubic root of 21140442 is about 276.5060815490.

Adding to 21140442 its reverse (24404112), we get a palindrome (45544554).

The spelling of 21140442 in words is "twenty-one million, one hundred forty thousand, four hundred forty-two".