21761191 has 2 divisors, whose sum is σ = 21761192. Its totient is φ = 21761190.

The previous prime is 21761167. The next prime is 21761219. The reversal of 21761191 is 19116712.

It is an a-pointer prime, because the next prime (21761219) can be obtained adding 21761191 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21761191 - 2⁹ = 21760679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21761161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10880595 + 10880596.

It is an arithmetic number, because the mean of its divisors is an integer number (10880596).

Almost surely, 2^21761191 is an apocalyptic number.

21761191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21761191 is an equidigital number, since it uses as much as digits as its factorization.

21761191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 756, while the sum is 28.

The square root of 21761191 is about 4664.8891733888. The cubic root of 21761191 is about 279.1863753022.

It can be divided in two parts, 21761 and 191, that added together give a cube (21952 = 28³).

The spelling of 21761191 in words is "twenty-one million, seven hundred sixty-one thousand, one hundred ninety-one".