21072006 has 12 divisors (see below), whose sum is σ = 45656052. Its totient is φ = 7023996.

The previous prime is 21071987. The next prime is 21072011. The reversal of 21072006 is 60027012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1170667 = 21072006 / (2 + 1 + 0 + 7 + 2 + 0 + 0 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 21072006.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 585316 + ... + 585351.

It is an arithmetic number, because the mean of its divisors is an integer number (3804671).

Almost surely, 2^21072006 is an apocalyptic number.

21072006 is an abundant number, since it is smaller than the sum of its proper divisors (24584046).

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

21072006 is a wasteful number, since it uses less digits than its factorization.

21072006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1170675 (or 1170672 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21072006 is about 4590.4254704766. The cubic root of 21072006 is about 276.2073898094.

Adding to 21072006 its reverse (60027012), we get a palindrome (81099018).

The spelling of 21072006 in words is "twenty-one million, seventy-two thousand, six".