21042142 has 12 divisors (see below), whose sum is σ = 34693848. Its totient is φ = 9564500.

The previous prime is 21042127. The next prime is 21042157. The reversal of 21042142 is 24124012.

It is an interprime number because it is at equal distance from previous prime (21042127) and next prime (21042157).

It is a congruent number.

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, 43234 + ... + 43717.

It is an arithmetic number, because the mean of its divisors is an integer number (2891154).

Almost surely, 2^21042142 is an apocalyptic number.

21042142 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21042142 is a deficient number, since it is larger than the sum of its proper divisors (13651706).

21042142 is a wasteful number, since it uses less digits than its factorization.

21042142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86975 (or 86964 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21042142 is about 4587.1714596252. The cubic root of 21042142 is about 276.0768444573.

Adding to 21042142 its reverse (24124012), we get a palindrome (45166154).

The spelling of 21042142 in words is "twenty-one million, forty-two thousand, one hundred forty-two".