21173878241 has 2 divisors, whose sum is σ = 21173878242. Its totient is φ = 21173878240.

The previous prime is 21173878181. The next prime is 21173878249. The reversal of 21173878241 is 14287837112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16883104225 + 4290774016 = 129935^2 + 65504^2 .

It is a cyclic number.

It is not a de Polignac number, because 21173878241 - 2²² = 21169683937 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21173878192 and 21173878201.

It is not a weakly prime, because it can be changed into another prime (21173878249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10586939120 + 10586939121.

It is an arithmetic number, because the mean of its divisors is an integer number (10586939121).

Almost surely, 2^21173878241 is an apocalyptic number.

It is an amenable number.

21173878241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21173878241 is an equidigital number, since it uses as much as digits as its factorization.

21173878241 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 150528, while the sum is 44.

The spelling of 21173878241 in words is "twenty-one billion, one hundred seventy-three million, eight hundred seventy-eight thousand, two hundred forty-one".