21611301660 has 192 divisors, whose sum is σ = 72569548800. Its totient is φ = 5307773184.

The previous prime is 21611301637. The next prime is 21611301713. The reversal of 21611301660 is 6610311612.

21611301660 is a `hidden beast` number, since 2 + 1 + 611 + 30 + 16 + 6 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3359367 + ... + 3365793.

It is an arithmetic number, because the mean of its divisors is an integer number (377966400).

Almost surely, 2^21611301660 is an apocalyptic number.

21611301660 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 21611301660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36284774400).

21611301660 is an abundant number, since it is smaller than the sum of its proper divisors (50958247140).

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

21611301660 is a wasteful number, since it uses less digits than its factorization.

21611301660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6937 (or 6929 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The spelling of 21611301660 in words is "twenty-one billion, six hundred eleven million, three hundred one thousand, six hundred sixty".