21239680 has 128 divisors (see below), whose sum is σ = 63452160. Its totient is φ = 6604800.

The previous prime is 21239671. The next prime is 21239689. The reversal of 21239680 is 8693212.

It is an interprime number because it is at equal distance from previous prime (21239671) and next prime (21239689).

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×21239680² = 902248013004800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21239689) 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, 49065 + ... + 49495.

It is an arithmetic number, because the mean of its divisors is an integer number (495720).

Almost surely, 2^21239680 is an apocalyptic number.

21239680 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 21239680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31726080).

21239680 is an abundant number, since it is smaller than the sum of its proper divisors (42212480).

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

21239680 is a wasteful number, since it uses less digits than its factorization.

21239680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468 (or 456 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21239680 is about 4608.6527315475. The cubic root of 21239680 is about 276.9380669315.

The spelling of 21239680 in words is "twenty-one million, two hundred thirty-nine thousand, six hundred eighty".