21343642 has 4 divisors (see below), whose sum is σ = 32015466. Its totient is φ = 10671820.

The previous prime is 21343633. The next prime is 21343643. The reversal of 21343642 is 24634312.

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., 18584721 + 2758921 = 4311^2 + 1661^2 .

It is not an unprimeable number, because it can be changed into a prime (21343643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5335909 + ... + 5335912.

Almost surely, 2^21343642 is an apocalyptic number.

21343642 is a deficient number, since it is larger than the sum of its proper divisors (10671824).

21343642 is a wasteful number, since it uses less digits than its factorization.

21343642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10671823.

The product of its digits is 3456, while the sum is 25.

The square root of 21343642 is about 4619.9179646396. The cubic root of 21343642 is about 277.3891752357.

Adding to 21343642 its reverse (24634312), we get a palindrome (45977954).

It can be divided in two parts, 2134 and 3642, that added together give a square (5776 = 76²).

The spelling of 21343642 in words is "twenty-one million, three hundred forty-three thousand, six hundred forty-two".