561401021 has 2 divisors, whose sum is σ = 561401022. Its totient is φ = 561401020.

The previous prime is 561401011. The next prime is 561401033. The reversal of 561401021 is 120104165.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 558376900 + 3024121 = 23630^2 + 1739^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-561401021 is a prime.

It is a super-2 number, since 2×561401021² = 630342212759684882, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 561400984 and 561401002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (561401011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280700510 + 280700511.

It is an arithmetic number, because the mean of its divisors is an integer number (280700511).

Almost surely, 2^561401021 is an apocalyptic number.

It is an amenable number.

561401021 is a deficient number, since it is larger than the sum of its proper divisors (1).

561401021 is an equidigital number, since it uses as much as digits as its factorization.

561401021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 561401021 is about 23693.9026122756. The cubic root of 561401021 is about 824.9438693369.

Adding to 561401021 its reverse (120104165), we get a palindrome (681505186).

The spelling of 561401021 in words is "five hundred sixty-one million, four hundred one thousand, twenty-one".