21605060 has 24 divisors (see below), whose sum is σ = 45503640. Its totient is φ = 8616704.

The previous prime is 21605057. The next prime is 21605063. The reversal of 21605060 is 6050612.

It is an interprime number because it is at equal distance from previous prime (21605057) and next prime (21605063).

It can be written as a sum of positive squares in 4 ways, for example, as 1156 + 21603904 = 34^2 + 4648^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21605063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6392 + ... + 9168.

It is an arithmetic number, because the mean of its divisors is an integer number (1895985).

Almost surely, 2^21605060 is an apocalyptic number.

21605060 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21605060 is an abundant number, since it is smaller than the sum of its proper divisors (23898580).

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

21605060 is a wasteful number, since it uses less digits than its factorization.

21605060 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3175 (or 3173 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21605060 is about 4648.1243528976. The cubic root of 21605060 is about 278.5170750221.

Adding to 21605060 its reverse (6050612), we get a palindrome (27655672).

The spelling of 21605060 in words is "twenty-one million, six hundred five thousand, sixty".