21507526742021 has 2 divisors, whose sum is σ = 21507526742022. Its totient is φ = 21507526742020.

The previous prime is 21507526741999. The next prime is 21507526742033. The reversal of 21507526742021 is 12024762570512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20957296591396 + 550230150625 = 4577914^2 + 741775^2 .

It is a cyclic number.

It is not a de Polignac number, because 21507526742021 - 2²² = 21507522547717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21507526742041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753763371010 + 10753763371011.

It is an arithmetic number, because the mean of its divisors is an integer number (10753763371011).

Almost surely, 2^{21507526742021} is an apocalyptic number.

It is an amenable number.

21507526742021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21507526742021 is an equidigital number, since it uses as much as digits as its factorization.

21507526742021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 470400, while the sum is 44.

The spelling of 21507526742021 in words is "twenty-one trillion, five hundred seven billion, five hundred twenty-six million, seven hundred forty-two thousand, twenty-one".