20723222561 has 2 divisors, whose sum is σ = 20723222562. Its totient is φ = 20723222560.

The previous prime is 20723222503. The next prime is 20723222591. The reversal of 20723222561 is 16522232702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19495140625 + 1228081936 = 139625^2 + 35044^2 .

It is a cyclic number.

It is not a de Polignac number, because 20723222561 - 2²⁶ = 20656113697 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20723222591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10361611280 + 10361611281.

It is an arithmetic number, because the mean of its divisors is an integer number (10361611281).

Almost surely, 2^20723222561 is an apocalyptic number.

It is an amenable number.

20723222561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20723222561 is an equidigital number, since it uses as much as digits as its factorization.

20723222561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20160, while the sum is 32.

The spelling of 20723222561 in words is "twenty billion, seven hundred twenty-three million, two hundred twenty-two thousand, five hundred sixty-one".