21235406 has 4 divisors (see below), whose sum is σ = 31853112. Its totient is φ = 10617702.

The previous prime is 21235367. The next prime is 21235427. The reversal of 21235406 is 60453212.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5308850 + ... + 5308853.

It is an arithmetic number, because the mean of its divisors is an integer number (7963278).

Almost surely, 2^21235406 is an apocalyptic number.

21235406 is a deficient number, since it is larger than the sum of its proper divisors (10617706).

21235406 is a wasteful number, since it uses less digits than its factorization.

21235406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10617705.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21235406 is about 4608.1890152206. The cubic root of 21235406 is about 276.9194898673.

Adding to 21235406 its reverse (60453212), we get a palindrome (81688618).

The spelling of 21235406 in words is "twenty-one million, two hundred thirty-five thousand, four hundred six".