20506729 has 2 divisors, whose sum is σ = 20506730. Its totient is φ = 20506728.

The previous prime is 20506723. The next prime is 20506747. The reversal of 20506729 is 92760502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15031129 + 5475600 = 3877^2 + 2340^2 .

It is a cyclic number.

It is not a de Polignac number, because 20506729 - 2¹¹ = 20504681 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20506729.

It is not a weakly prime, because it can be changed into another prime (20506723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10253364 + 10253365.

It is an arithmetic number, because the mean of its divisors is an integer number (10253365).

Almost surely, 2^20506729 is an apocalyptic number.

It is an amenable number.

20506729 is a deficient number, since it is larger than the sum of its proper divisors (1).

20506729 is an equidigital number, since it uses as much as digits as its factorization.

20506729 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 20506729 is about 4528.4356018387. The cubic root of 20506729 is about 273.7151256283.

The spelling of 20506729 in words is "twenty million, five hundred six thousand, seven hundred twenty-nine".