21009465739 has 2 divisors, whose sum is σ = 21009465740. Its totient is φ = 21009465738.

The previous prime is 21009465727. The next prime is 21009465749. The reversal of 21009465739 is 93756490012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21009465739 - 2¹⁷ = 21009334667 is a prime.

It is a super-2 number, since 2×21009465739² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21009465749) 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, 10504732869 + 10504732870.

It is an arithmetic number, because the mean of its divisors is an integer number (10504732870).

Almost surely, 2^21009465739 is an apocalyptic number.

21009465739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21009465739 is an equidigital number, since it uses as much as digits as its factorization.

21009465739 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 408240, while the sum is 46.

The spelling of 21009465739 in words is "twenty-one billion, nine million, four hundred sixty-five thousand, seven hundred thirty-nine".