21340687680 has 784 divisors, whose sum is σ = 85072264704. Its totient is φ = 5061242880.

The previous prime is 21340687663. The next prime is 21340687699. The reversal of 21340687680 is 8678604312.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 94011727 + ... + 94011953.

Almost surely, 2^21340687680 is an apocalyptic number.

21340687680 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 21340687680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42536132352).

21340687680 is an abundant number, since it is smaller than the sum of its proper divisors (63731577024).

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

21340687680 is a wasteful number, since it uses less digits than its factorization.

21340687680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 21340687680 in words is "twenty-one billion, three hundred forty million, six hundred eighty-seven thousand, six hundred eighty".