21305142 has 24 divisors (see below), whose sum is σ = 46622160. Its totient is φ = 7030800.

The previous prime is 21305113. The next prime is 21305149. The reversal of 21305142 is 24150312.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305149) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4042 + ... + 7677.

It is an arithmetic number, because the mean of its divisors is an integer number (1942590).

Almost surely, 2^21305142 is an apocalyptic number.

21305142 is an abundant number, since it is smaller than the sum of its proper divisors (25317018).

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

21305142 is a wasteful number, since it uses less digits than its factorization.

21305142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11828 (or 11825 counting only the distinct ones).

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

The square root of 21305142 is about 4615.7493432811. The cubic root of 21305142 is about 277.2222885197. Note that the first 4 decimals are identical.

Adding to 21305142 its reverse (24150312), we get a palindrome (45455454).

The spelling of 21305142 in words is "twenty-one million, three hundred five thousand, one hundred forty-two".