21696506 has 16 divisors (see below), whose sum is σ = 35152488. Its totient is φ = 9984000.

The previous prime is 21696491. The next prime is 21696511. The reversal of 21696506 is 60569612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 19722481 + 1974025 = 4441^2 + 1405^2 .

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, 9386 + ... + 11466.

Almost surely, 2^21696506 is an apocalyptic number.

21696506 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21696506 is a deficient number, since it is larger than the sum of its proper divisors (13455982).

21696506 is a wasteful number, since it uses less digits than its factorization.

21696506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2497.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 21696506 is about 4657.9508370098. The cubic root of 21696506 is about 278.9094741914.

The spelling of 21696506 in words is "twenty-one million, six hundred ninety-six thousand, five hundred six".