21523042 has 4 divisors (see below), whose sum is σ = 32284566. Its totient is φ = 10761520.

The previous prime is 21523001. The next prime is 21523049. The reversal of 21523042 is 24032512.

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., 14130081 + 7392961 = 3759^2 + 2719^2 .

It is not an unprimeable number, because it can be changed into a prime (21523049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5380759 + ... + 5380762.

Almost surely, 2^21523042 is an apocalyptic number.

21523042 is a deficient number, since it is larger than the sum of its proper divisors (10761524).

21523042 is a wasteful number, since it uses less digits than its factorization.

21523042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10761523.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 21523042 is about 4639.2932651429. The cubic root of 21523042 is about 278.1641888473.

Adding to 21523042 its reverse (24032512), we get a palindrome (45555554).

The spelling of 21523042 in words is "twenty-one million, five hundred twenty-three thousand, forty-two".