21307207680 has 832 divisors, whose sum is σ = 86056611840. Its totient is φ = 4954521600.

The previous prime is 21307207673. The next prime is 21307207687. The reversal of 21307207680 is 8670270312.

It is an interprime number because it is at equal distance from previous prime (21307207673) and next prime (21307207687).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21307207687) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 188559304 + ... + 188559416.

Almost surely, 2^21307207680 is an apocalyptic number.

21307207680 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 21307207680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43028305920).

21307207680 is an abundant number, since it is smaller than the sum of its proper divisors (64749404160).

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

21307207680 is a wasteful number, since it uses less digits than its factorization.

21307207680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193 (or 165 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 36.

Adding to 21307207680 its reverse (8670270312), we get a palindrome (29977477992).

The spelling of 21307207680 in words is "twenty-one billion, three hundred seven million, two hundred seven thousand, six hundred eighty".