21661068 has 72 divisors (see below), whose sum is σ = 59766336. Its totient is φ = 6052800.

The previous prime is 21661061. The next prime is 21661097. The reversal of 21661068 is 86016612.

It is not an unprimeable number, because it can be changed into a prime (21661061) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21823 + ... + 22793.

It is an arithmetic number, because the mean of its divisors is an integer number (830088).

Almost surely, 2^21661068 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21661068, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29883168).

21661068 is an abundant number, since it is smaller than the sum of its proper divisors (38105268).

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

21661068 is a wasteful number, since it uses less digits than its factorization.

21661068 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1015 (or 1000 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21661068 is about 4654.1452491301. The cubic root of 21661068 is about 278.7575391259.

The spelling of 21661068 in words is "twenty-one million, six hundred sixty-one thousand, sixty-eight".