21072066 has 8 divisors (see below), whose sum is σ = 42144144. Its totient is φ = 7024020.

The previous prime is 21072053. The next prime is 21072101. The reversal of 21072066 is 66027012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

21072066 is an admirable number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1756000 + ... + 1756011.

It is an arithmetic number, because the mean of its divisors is an integer number (5268018).

Almost surely, 2^21072066 is an apocalyptic number.

21072066 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21072066 is a wasteful number, since it uses less digits than its factorization.

21072066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3512016.

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21072066 is about 4590.4320058138. The cubic root of 21072066 is about 276.2076519649.

Adding to 21072066 its reverse (66027012), we get a palindrome (87099078).

The spelling of 21072066 in words is "twenty-one million, seventy-two thousand, sixty-six".