21542432450521 has 2 divisors, whose sum is σ = 21542432450522. Its totient is φ = 21542432450520.

The previous prime is 21542432450411. The next prime is 21542432450587. The reversal of 21542432450521 is 12505423424512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21348511998025 + 193920452496 = 4620445^2 + 440364^2 .

It is a cyclic number.

It is not a de Polignac number, because 21542432450521 - 2⁷ = 21542432450393 is a prime.

It is a super-2 number, since 2×21542432450521² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21542432450221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771216225260 + 10771216225261.

It is an arithmetic number, because the mean of its divisors is an integer number (10771216225261).

Almost surely, 2^{21542432450521} is an apocalyptic number.

It is an amenable number.

21542432450521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542432450521 is an equidigital number, since it uses as much as digits as its factorization.

21542432450521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 384000, while the sum is 40.

The spelling of 21542432450521 in words is "twenty-one trillion, five hundred forty-two billion, four hundred thirty-two million, four hundred fifty thousand, five hundred twenty-one".