20355961 has 2 divisors, whose sum is σ = 20355962. Its totient is φ = 20355960.

The previous prime is 20355949. The next prime is 20356013. The reversal of 20355961 is 16955302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18224361 + 2131600 = 4269^2 + 1460^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20355961 is a prime.

It is not a weakly prime, because it can be changed into another prime (20355931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10177980 + 10177981.

It is an arithmetic number, because the mean of its divisors is an integer number (10177981).

Almost surely, 2^20355961 is an apocalyptic number.

It is an amenable number.

20355961 is a deficient number, since it is larger than the sum of its proper divisors (1).

20355961 is an equidigital number, since it uses as much as digits as its factorization.

20355961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 20355961 is about 4511.7580830537. The cubic root of 20355961 is about 273.0426791723.

It can be divided in two parts, 20355 and 961, that added together give a square (21316 = 146²).

The spelling of 20355961 in words is "twenty million, three hundred fifty-five thousand, nine hundred sixty-one".