21424874561 has 2 divisors, whose sum is σ = 21424874562. Its totient is φ = 21424874560.

The previous prime is 21424874519. The next prime is 21424874567. The reversal of 21424874561 is 16547842412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20994561025 + 430313536 = 144895^2 + 20744^2 .

It is a cyclic number.

It is not a de Polignac number, because 21424874561 - 2²⁶ = 21357765697 is a prime.

It is not a weakly prime, because it can be changed into another prime (21424874567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712437280 + 10712437281.

It is an arithmetic number, because the mean of its divisors is an integer number (10712437281).

Almost surely, 2^21424874561 is an apocalyptic number.

It is an amenable number.

21424874561 is a deficient number, since it is larger than the sum of its proper divisors (1).

21424874561 is an equidigital number, since it uses as much as digits as its factorization.

21424874561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 430080, while the sum is 44.

The spelling of 21424874561 in words is "twenty-one billion, four hundred twenty-four million, eight hundred seventy-four thousand, five hundred sixty-one".