21171739 has 2 divisors, whose sum is σ = 21171740. Its totient is φ = 21171738.

The previous prime is 21171727. The next prime is 21171743. The reversal of 21171739 is 93717112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21171739 - 2¹¹ = 21169691 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21171739.

It is not a weakly prime, because it can be changed into another prime (21171779) 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, 10585869 + 10585870.

It is an arithmetic number, because the mean of its divisors is an integer number (10585870).

Almost surely, 2^21171739 is an apocalyptic number.

21171739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21171739 is an equidigital number, since it uses as much as digits as its factorization.

21171739 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2646, while the sum is 31.

The square root of 21171739 is about 4601.2758013403. The cubic root of 21171739 is about 276.6424638108.

The spelling of 21171739 in words is "twenty-one million, one hundred seventy-one thousand, seven hundred thirty-nine".