21610836 has 72 divisors (see below), whose sum is σ = 59872904. Its totient is φ = 6531840.

The previous prime is 21610807. The next prime is 21610837. The reversal of 21610836 is 63801612.

It can be written as a sum of positive squares in 4 ways, for example, as 44100 + 21566736 = 210^2 + 4644^2 .

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21610837) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28170 + ... + 28926.

Almost surely, 2^21610836 is an apocalyptic number.

21610836 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21610836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29936452).

21610836 is an abundant number, since it is smaller than the sum of its proper divisors (38262068).

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

21610836 is a wasteful number, since it uses less digits than its factorization.

21610836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 841 (or 836 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21610836 is about 4648.7456372660. The cubic root of 21610836 is about 278.5418928393.

The spelling of 21610836 in words is "twenty-one million, six hundred ten thousand, eight hundred thirty-six".