21559739 has 2 divisors, whose sum is σ = 21559740. Its totient is φ = 21559738.

The previous prime is 21559709. The next prime is 21559777. The reversal of 21559739 is 93795512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21559739 - 2²⁴ = 4782523 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21559696 and 21559705.

It is not a weakly prime, because it can be changed into another prime (21559709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10779869 + 10779870.

It is an arithmetic number, because the mean of its divisors is an integer number (10779870).

Almost surely, 2^21559739 is an apocalyptic number.

21559739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21559739 is an equidigital number, since it uses as much as digits as its factorization.

21559739 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 85050, while the sum is 41.

The square root of 21559739 is about 4643.2466012479. The cubic root of 21559739 is about 278.3221899834.

The spelling of 21559739 in words is "twenty-one million, five hundred fifty-nine thousand, seven hundred thirty-nine".