21197946 has 64 divisors (see below), whose sum is σ = 55987200. Its totient is φ = 5180160.

The previous prime is 21197923. The next prime is 21197947. The reversal of 21197946 is 64979112.

It is not an unprimeable number, because it can be changed into a prime (21197947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6505 + ... + 9203.

It is an arithmetic number, because the mean of its divisors is an integer number (874800).

Almost surely, 2^21197946 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21197946, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27993600).

21197946 is an abundant number, since it is smaller than the sum of its proper divisors (34789254).

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

21197946 is a wasteful number, since it uses less digits than its factorization.

21197946 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2739.

The product of its digits is 27216, while the sum is 39.

The square root of 21197946 is about 4604.1227177390. The cubic root of 21197946 is about 276.7565621330.

The spelling of 21197946 in words is "twenty-one million, one hundred ninety-seven thousand, nine hundred forty-six".