21742379 has 2 divisors, whose sum is σ = 21742380. Its totient is φ = 21742378.

The previous prime is 21742363. The next prime is 21742381. The reversal of 21742379 is 97324712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21742379 - 2⁴ = 21742363 is a prime.

Together with 21742381, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21742319) 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 as a sum of consecutive naturals, namely, 10871189 + 10871190.

It is an arithmetic number, because the mean of its divisors is an integer number (10871190).

Almost surely, 2^21742379 is an apocalyptic number.

21742379 is a deficient number, since it is larger than the sum of its proper divisors (1).

21742379 is an equidigital number, since it uses as much as digits as its factorization.

21742379 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21168, while the sum is 35.

The square root of 21742379 is about 4662.8723979968. The cubic root of 21742379 is about 279.1059022521.

The spelling of 21742379 in words is "twenty-one million, seven hundred forty-two thousand, three hundred seventy-nine".