21766836 has 96 divisors (see below), whose sum is σ = 64626688. Its totient is φ = 5546880.

The previous prime is 21766831. The next prime is 21766853. The reversal of 21766836 is 63866712.

21766836 = T₃₃₅ + T₃₃₆ + ... + T₅₅₁.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a junction number, because it is equal to n+sod(n) for n = 21766794 and 21766803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21766831) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33531 + ... + 34173.

Almost surely, 2^21766836 is an apocalyptic number.

21766836 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 21766836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32313344).

21766836 is an abundant number, since it is smaller than the sum of its proper divisors (42859852).

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

21766836 is a wasteful number, since it uses less digits than its factorization.

21766836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 701 (or 699 counting only the distinct ones).

The product of its digits is 72576, while the sum is 39.

The square root of 21766836 is about 4665.4941860429. The cubic root of 21766836 is about 279.2105141592.

The spelling of 21766836 in words is "twenty-one million, seven hundred sixty-six thousand, eight hundred thirty-six".