21909246 has 16 divisors (see below), whose sum is σ = 44645904. Its totient is φ = 7165184.

The previous prime is 21909229. The next prime is 21909247. The reversal of 21909246 is 64290912.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21909247) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34131 + ... + 34766.

It is an arithmetic number, because the mean of its divisors is an integer number (2790369).

Almost surely, 2^21909246 is an apocalyptic number.

21909246 is an abundant number, since it is smaller than the sum of its proper divisors (22736658).

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

21909246 is a wasteful number, since it uses less digits than its factorization.

21909246 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68955.

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 21909246 is about 4680.7313531114. The cubic root of 21909246 is about 279.8181046507.

It can be divided in two parts, 21909 and 246, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21909246 in words is "twenty-one million, nine hundred nine thousand, two hundred forty-six".