21097206 has 64 divisors (see below), whose sum is σ = 51791040. Its totient is φ = 6324480.

The previous prime is 21097171. The next prime is 21097207. The reversal of 21097206 is 60279012.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21097206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21097207) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28416 + ... + 29148.

It is an arithmetic number, because the mean of its divisors is an integer number (809235).

Almost surely, 2^21097206 is an apocalyptic number.

21097206 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21097206, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25895520).

21097206 is an abundant number, since it is smaller than the sum of its proper divisors (30693834).

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

21097206 is a wasteful number, since it uses less digits than its factorization.

21097206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798 (or 792 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21097206 is about 4593.1694939334. The cubic root of 21097206 is about 276.3174513670.

The spelling of 21097206 in words is "twenty-one million, ninety-seven thousand, two hundred six".