20001220961 has 2 divisors, whose sum is σ = 20001220962. Its totient is φ = 20001220960.

The previous prime is 20001220949. The next prime is 20001220997. The reversal of 20001220961 is 16902210002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18473974561 + 1527246400 = 135919^2 + 39080^2 .

It is a cyclic number.

It is not a de Polignac number, because 20001220961 - 2¹⁴ = 20001204577 is a prime.

It is not a weakly prime, because it can be changed into another prime (20001220361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000610480 + 10000610481.

It is an arithmetic number, because the mean of its divisors is an integer number (10000610481).

Almost surely, 2^20001220961 is an apocalyptic number.

It is an amenable number.

20001220961 is a deficient number, since it is larger than the sum of its proper divisors (1).

20001220961 is an equidigital number, since it uses as much as digits as its factorization.

20001220961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

Adding to 20001220961 its reverse (16902210002), we get a palindrome (36903430963).

The spelling of 20001220961 in words is "twenty billion, one million, two hundred twenty thousand, nine hundred sixty-one".