21123142 has 4 divisors (see below), whose sum is σ = 31684716. Its totient is φ = 10561570.

The previous prime is 21123133. The next prime is 21123143. The reversal of 21123142 is 24132112.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5280784 + ... + 5280787.

It is an arithmetic number, because the mean of its divisors is an integer number (7921179).

Almost surely, 2^21123142 is an apocalyptic number.

21123142 is a deficient number, since it is larger than the sum of its proper divisors (10561574).

21123142 is a wasteful number, since it uses less digits than its factorization.

21123142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10561573.

The product of its digits is 96, while the sum is 16.

The square root of 21123142 is about 4595.9919495143. The cubic root of 21123142 is about 276.4306359386.

Adding to 21123142 its reverse (24132112), we get a palindrome (45255254).

The spelling of 21123142 in words is "twenty-one million, one hundred twenty-three thousand, one hundred forty-two".