21161279 has 2 divisors, whose sum is σ = 21161280. Its totient is φ = 21161278.

The previous prime is 21161237. The next prime is 21161281. The reversal of 21161279 is 97216112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21161279 - 2¹⁶ = 21095743 is a prime.

It is a Sophie Germain prime.

Together with 21161281, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21161779) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10580639 + 10580640.

It is an arithmetic number, because the mean of its divisors is an integer number (10580640).

Almost surely, 2^21161279 is an apocalyptic number.

21161279 is a deficient number, since it is larger than the sum of its proper divisors (1).

21161279 is an equidigital number, since it uses as much as digits as its factorization.

21161279 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1512, while the sum is 29.

The square root of 21161279 is about 4600.1390196384. The cubic root of 21161279 is about 276.5968974570.

The spelling of 21161279 in words is "twenty-one million, one hundred sixty-one thousand, two hundred seventy-nine".