21697339 has 2 divisors, whose sum is σ = 21697340. Its totient is φ = 21697338.

The previous prime is 21697301. The next prime is 21697343. The reversal of 21697339 is 93379612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21697339 - 2¹¹ = 21695291 is a prime.

It is not a weakly prime, because it can be changed into another prime (21697369) 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, 10848669 + 10848670.

It is an arithmetic number, because the mean of its divisors is an integer number (10848670).

Almost surely, 2^21697339 is an apocalyptic number.

21697339 is a deficient number, since it is larger than the sum of its proper divisors (1).

21697339 is an equidigital number, since it uses as much as digits as its factorization.

21697339 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 61236, while the sum is 40.

The square root of 21697339 is about 4658.0402531537. The cubic root of 21697339 is about 278.9130435621.

The spelling of 21697339 in words is "twenty-one million, six hundred ninety-seven thousand, three hundred thirty-nine".