21660006 has 16 divisors (see below), whose sum is σ = 45868464. Its totient is φ = 6795264.

The previous prime is 21659999. The next prime is 21660007. The reversal of 21660006 is 60006612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660007) 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, 106075 + ... + 106278.

It is an arithmetic number, because the mean of its divisors is an integer number (2866779).

Almost surely, 2^21660006 is an apocalyptic number.

21660006 is an abundant number, since it is smaller than the sum of its proper divisors (24208458).

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

21660006 is a wasteful number, since it uses less digits than its factorization.

21660006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212375.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21660006 is about 4654.0311558906. The cubic root of 21660006 is about 278.7529834050.

Adding to 21660006 its reverse (60006612), we get a palindrome (81666618).

The spelling of 21660006 in words is "twenty-one million, six hundred sixty thousand, six".