21205530739 has 2 divisors, whose sum is σ = 21205530740. Its totient is φ = 21205530738.

The previous prime is 21205530727. The next prime is 21205530757. The reversal of 21205530739 is 93703550212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21205530739 - 2³¹ = 19058047091 is a prime.

It is a super-2 number, since 2×21205530739² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21205530698 and 21205530707.

It is not a weakly prime, because it can be changed into another prime (21205530719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602765369 + 10602765370.

It is an arithmetic number, because the mean of its divisors is an integer number (10602765370).

Almost surely, 2^21205530739 is an apocalyptic number.

21205530739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21205530739 is an equidigital number, since it uses as much as digits as its factorization.

21205530739 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 56700, while the sum is 37.

The spelling of 21205530739 in words is "twenty-one billion, two hundred five million, five hundred thirty thousand, seven hundred thirty-nine".