21576937561 has 2 divisors, whose sum is σ = 21576937562. Its totient is φ = 21576937560.

The previous prime is 21576937517. The next prime is 21576937579. The reversal of 21576937561 is 16573967512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17647528336 + 3929409225 = 132844^2 + 62685^2 .

It is a cyclic number.

It is not a de Polignac number, because 21576937561 - 2⁷ = 21576937433 is a prime.

It is a super-2 number, since 2×21576937561² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21576937499 and 21576937508.

It is not a weakly prime, because it can be changed into another prime (21576937861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10788468780 + 10788468781.

It is an arithmetic number, because the mean of its divisors is an integer number (10788468781).

Almost surely, 2^21576937561 is an apocalyptic number.

It is an amenable number.

21576937561 is a deficient number, since it is larger than the sum of its proper divisors (1).

21576937561 is an equidigital number, since it uses as much as digits as its factorization.

21576937561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2381400, while the sum is 52.

The spelling of 21576937561 in words is "twenty-one billion, five hundred seventy-six million, nine hundred thirty-seven thousand, five hundred sixty-one".