21688335340 has 24 divisors (see below), whose sum is σ = 52052005152. Its totient is φ = 7436000640.

The previous prime is 21688335337. The next prime is 21688335343. The reversal of 21688335340 is 4353388612.

It is an interprime number because it is at equal distance from previous prime (21688335337) and next prime (21688335343).

It is not an unprimeable number, because it can be changed into a prime (21688335343) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77458201 + ... + 77458480.

It is an arithmetic number, because the mean of its divisors is an integer number (2168833548).

Almost surely, 2^21688335340 is an apocalyptic number.

21688335340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21688335340 is an abundant number, since it is smaller than the sum of its proper divisors (30363669812).

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

21688335340 is a wasteful number, since it uses less digits than its factorization.

21688335340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154916697 (or 154916695 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 43.

The spelling of 21688335340 in words is "twenty-one billion, six hundred eighty-eight million, three hundred thirty-five thousand, three hundred forty".