21100072 has 16 divisors (see below), whose sum is σ = 45214560. Its totient is φ = 9042864.

The previous prime is 21100069. The next prime is 21100087. The reversal of 21100072 is 27000112.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 188338 + ... + 188449.

It is an arithmetic number, because the mean of its divisors is an integer number (2825910).

Almost surely, 2^21100072 is an apocalyptic number.

It is an amenable number.

21100072 is an abundant number, since it is smaller than the sum of its proper divisors (24114488).

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

21100072 is a wasteful number, since it uses less digits than its factorization.

21100072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376800 (or 376796 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 21100072 is about 4593.4814683419. The cubic root of 21100072 is about 276.3299631337.

Adding to 21100072 its reverse (27000112), we get a palindrome (48100184).

The spelling of 21100072 in words is "twenty-one million, one hundred thousand, seventy-two".