21243937061 has 2 divisors, whose sum is σ = 21243937062. Its totient is φ = 21243937060.

The previous prime is 21243937019. The next prime is 21243937079. The reversal of 21243937061 is 16073934212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20823933025 + 420004036 = 144305^2 + 20494^2 .

It is a cyclic number.

It is not a de Polignac number, because 21243937061 - 2⁶ = 21243936997 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21243937261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621968530 + 10621968531.

It is an arithmetic number, because the mean of its divisors is an integer number (10621968531).

Almost surely, 2^21243937061 is an apocalyptic number.

It is an amenable number.

21243937061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243937061 is an equidigital number, since it uses as much as digits as its factorization.

21243937061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54432, while the sum is 38.

The spelling of 21243937061 in words is "twenty-one billion, two hundred forty-three million, nine hundred thirty-seven thousand, sixty-one".