21123760 has 80 divisors (see below), whose sum is σ = 57067776. Its totient is φ = 7121664.

The previous prime is 21123757. The next prime is 21123761. The reversal of 21123760 is 6732112.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (21123761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37239 + ... + 37801.

Almost surely, 2^21123760 is an apocalyptic number.

21123760 is a gapful number since it is divisible by the number (20) 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 21123760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28533888).

21123760 is an abundant number, since it is smaller than the sum of its proper divisors (35944016).

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

21123760 is a wasteful number, since it uses less digits than its factorization.

21123760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650 (or 644 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 21123760 is about 4596.0591815163. The cubic root of 21123760 is about 276.4333317570.

Adding to 21123760 its reverse (6732112), we get a palindrome (27855872).

The spelling of 21123760 in words is "twenty-one million, one hundred twenty-three thousand, seven hundred sixty".