21626197 has 2 divisors, whose sum is σ = 21626198. Its totient is φ = 21626196.

The previous prime is 21626183. The next prime is 21626201. The reversal of 21626197 is 79162612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21613201 + 12996 = 4649^2 + 114^2 .

It is a cyclic number.

It is not a de Polignac number, because 21626197 - 2¹⁹ = 21101909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21626497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10813098 + 10813099.

It is an arithmetic number, because the mean of its divisors is an integer number (10813099).

Almost surely, 2^21626197 is an apocalyptic number.

It is an amenable number.

21626197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21626197 is an equidigital number, since it uses as much as digits as its factorization.

21626197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 34.

The square root of 21626197 is about 4650.3975098910. The cubic root of 21626197 is about 278.6078731443.

The spelling of 21626197 in words is "twenty-one million, six hundred twenty-six thousand, one hundred ninety-seven".