561858950021 has 2 divisors, whose sum is σ = 561858950022. Its totient is φ = 561858950020.

The previous prime is 561858949957. The next prime is 561858950027. The reversal of 561858950021 is 120059858165.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 459595864225 + 102263085796 = 677935^2 + 319786^2 .

It is a cyclic number.

It is not a de Polignac number, because 561858950021 - 2⁶ = 561858949957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (561858950027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280929475010 + 280929475011.

It is an arithmetic number, because the mean of its divisors is an integer number (280929475011).

Almost surely, 2^561858950021 is an apocalyptic number.

It is an amenable number.

561858950021 is a deficient number, since it is larger than the sum of its proper divisors (1).

561858950021 is an equidigital number, since it uses as much as digits as its factorization.

561858950021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864000, while the sum is 50.

The spelling of 561858950021 in words is "five hundred sixty-one billion, eight hundred fifty-eight million, nine hundred fifty thousand, twenty-one".