21661060 has 24 divisors (see below), whose sum is σ = 48164760. Its totient is φ = 8154624.

The previous prime is 21661051. The next prime is 21661061. The reversal of 21661060 is 6016612.

It can be written as a sum of positive squares in 4 ways, for example, as 1085764 + 20575296 = 1042^2 + 4536^2 .

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 31515 + ... + 32194.

It is an arithmetic number, because the mean of its divisors is an integer number (2006865).

Almost surely, 2^21661060 is an apocalyptic number.

21661060 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21661060 is an abundant number, since it is smaller than the sum of its proper divisors (26503700).

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

21661060 is a wasteful number, since it uses less digits than its factorization.

21661060 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63735 (or 63733 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21661060 is about 4654.1443896811. The cubic root of 21661060 is about 278.7575048084.

Adding to 21661060 its reverse (6016612), we get a palindrome (27677672).

The spelling of 21661060 in words is "twenty-one million, six hundred sixty-one thousand, sixty".