1561621441 has 2 divisors, whose sum is σ = 1561621442. Its totient is φ = 1561621440.

The previous prime is 1561621433. The next prime is 1561621517. The reversal of 1561621441 is 1441261651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1190250000 + 371371441 = 34500^2 + 19271^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561621441 - 2³ = 1561621433 is a prime.

It is not a weakly prime, because it can be changed into another prime (1561621141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780810720 + 780810721.

It is an arithmetic number, because the mean of its divisors is an integer number (780810721).

Almost surely, 2^1561621441 is an apocalyptic number.

It is an amenable number.

1561621441 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561621441 is an equidigital number, since it uses as much as digits as its factorization.

1561621441 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 31.

The square root of 1561621441 is about 39517.3561995233. The cubic root of 1561621441 is about 1160.1796791131.

The spelling of 1561621441 in words is "one billion, five hundred sixty-one million, six hundred twenty-one thousand, four hundred forty-one".