21903197 has 2 divisors, whose sum is σ = 21903198. Its totient is φ = 21903196.

The previous prime is 21903187. The next prime is 21903229. The reversal of 21903197 is 79130912.

It is a happy number.

It is an a-pointer prime, because the next prime (21903229) can be obtained adding 21903197 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17859076 + 4044121 = 4226^2 + 2011^2 .

It is a cyclic number.

It is not a de Polignac number, because 21903197 - 2⁸ = 21902941 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21903187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10951598 + 10951599.

It is an arithmetic number, because the mean of its divisors is an integer number (10951599).

Almost surely, 2^21903197 is an apocalyptic number.

It is an amenable number.

21903197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21903197 is an equidigital number, since it uses as much as digits as its factorization.

21903197 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 21903197 is about 4680.0851487980. The cubic root of 21903197 is about 279.7923502955.

The spelling of 21903197 in words is "twenty-one million, nine hundred three thousand, one hundred ninety-seven".