21645739080 has 256 divisors, whose sum is σ = 84215808000. Its totient is φ = 4842249984.

The previous prime is 21645739061. The next prime is 21645739081. The reversal of 21645739080 is 8093754612.

21645739080 is a `hidden beast` number, since 216 + 45 + 7 + 390 + 8 + 0 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (21645739081) 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, 324861 + ... + 385779.

It is an arithmetic number, because the mean of its divisors is an integer number (328968000).

It is a 1-persistent number, because it is pandigital, but 2⋅21645739080 = 43291478160 is not.

Almost surely, 2^21645739080 is an apocalyptic number.

21645739080 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 21645739080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42107904000).

21645739080 is an abundant number, since it is smaller than the sum of its proper divisors (62570068920).

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

21645739080 is a wasteful number, since it uses less digits than its factorization.

21645739080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60993 (or 60983 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The spelling of 21645739080 in words is "twenty-one billion, six hundred forty-five million, seven hundred thirty-nine thousand, eighty".