21232506 has 16 divisors (see below), whose sum is σ = 43501248. Its totient is φ = 6904800.

The previous prime is 21232493. The next prime is 21232511. The reversal of 21232506 is 60523212.

It is a super-2 number, since 2×21232506² = 901638622080072, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42910 + ... + 43401.

It is an arithmetic number, because the mean of its divisors is an integer number (2718828).

Almost surely, 2^21232506 is an apocalyptic number.

21232506 is an abundant number, since it is smaller than the sum of its proper divisors (22268742).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21232506 is a wasteful number, since it uses less digits than its factorization.

21232506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86357.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21232506 is about 4607.8743472452. The cubic root of 21232506 is about 276.9068835142.

Adding to 21232506 its reverse (60523212), we get a palindrome (81755718).

The spelling of 21232506 in words is "twenty-one million, two hundred thirty-two thousand, five hundred six".