21964197 has 4 divisors (see below), whose sum is σ = 29285600. Its totient is φ = 14642796.

The previous prime is 21964193. The next prime is 21964219. The reversal of 21964197 is 79146912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21964197 - 2² = 21964193 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21964193) 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 3 ways as a sum of consecutive naturals, for example, 3660697 + ... + 3660702.

It is an arithmetic number, because the mean of its divisors is an integer number (7321400).

Almost surely, 2^21964197 is an apocalyptic number.

It is an amenable number.

21964197 is a deficient number, since it is larger than the sum of its proper divisors (7321403).

21964197 is an equidigital number, since it uses as much as digits as its factorization.

21964197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7321402.

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

The square root of 21964197 is about 4686.5975931373. The cubic root of 21964197 is about 280.0518483917.

The spelling of 21964197 in words is "twenty-one million, nine hundred sixty-four thousand, one hundred ninety-seven".