21105672 has 96 divisors (see below), whose sum is σ = 62298720. Its totient is φ = 5940480.

The previous prime is 21105671. The next prime is 21105677. The reversal of 21105672 is 27650112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21105671) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 153988 + ... + 154124.

It is an arithmetic number, because the mean of its divisors is an integer number (648945).

Almost surely, 2^21105672 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21105672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31149360).

21105672 is an abundant number, since it is smaller than the sum of its proper divisors (41193048).

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

21105672 is a wasteful number, since it uses less digits than its factorization.

21105672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 21105672 is about 4594.0909873445. The cubic root of 21105672 is about 276.3544071406.

Adding to 21105672 its reverse (27650112), we get a palindrome (48755784).

The spelling of 21105672 in words is "twenty-one million, one hundred five thousand, six hundred seventy-two".