21506060 has 12 divisors (see below), whose sum is σ = 45162768. Its totient is φ = 8602416.

The previous prime is 21506059. The next prime is 21506083. The reversal of 21506060 is 6060512.

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 1075303 = 21506060 / (2 + 1 + 5 + 0 + 6 + 0 + 6 + 0).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 537632 + ... + 537671.

It is an arithmetic number, because the mean of its divisors is an integer number (3763564).

Almost surely, 2^21506060 is an apocalyptic number.

21506060 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21506060 is an abundant number, since it is smaller than the sum of its proper divisors (23656708).

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

21506060 is a wasteful number, since it uses less digits than its factorization.

21506060 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075312 (or 1075310 counting only the distinct ones).

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

The square root of 21506060 is about 4637.4626683134. The cubic root of 21506060 is about 278.0910110381.

Adding to 21506060 its reverse (6060512), we get a palindrome (27566572).

The spelling of 21506060 in words is "twenty-one million, five hundred six thousand, sixty".