21523426 has 4 divisors (see below), whose sum is σ = 32285142. Its totient is φ = 10761712.

The previous prime is 21523421. The next prime is 21523433. The reversal of 21523426 is 62432512.

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., 13315201 + 8208225 = 3649^2 + 2865^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21523426.

It is not an unprimeable number, because it can be changed into a prime (21523421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5380855 + ... + 5380858.

Almost surely, 2^21523426 is an apocalyptic number.

21523426 is a deficient number, since it is larger than the sum of its proper divisors (10761716).

21523426 is a wasteful number, since it uses less digits than its factorization.

21523426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10761715.

The product of its digits is 2880, while the sum is 25.

The square root of 21523426 is about 4639.3346505722. The cubic root of 21523426 is about 278.1658431118.

Adding to 21523426 its reverse (62432512), we get a palindrome (83955938).

The spelling of 21523426 in words is "twenty-one million, five hundred twenty-three thousand, four hundred twenty-six".