21142546 has 4 divisors (see below), whose sum is σ = 31713822. Its totient is φ = 10571272.

The previous prime is 21142531. The next prime is 21142613. The reversal of 21142546 is 64524112.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 14356521 + 6786025 = 3789^2 + 2605^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21142546.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5285635 + ... + 5285638.

Almost surely, 2^21142546 is an apocalyptic number.

21142546 is a deficient number, since it is larger than the sum of its proper divisors (10571276).

21142546 is a wasteful number, since it uses less digits than its factorization.

21142546 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10571275.

The product of its digits is 1920, while the sum is 25.

The square root of 21142546 is about 4598.1024347006. The cubic root of 21142546 is about 276.5152543231.

Adding to 21142546 its reverse (64524112), we get a palindrome (85666658).

The spelling of 21142546 in words is "twenty-one million, one hundred forty-two thousand, five hundred forty-six".