21541255501 has 2 divisors, whose sum is σ = 21541255502. Its totient is φ = 21541255500.

The previous prime is 21541255451. The next prime is 21541255507. The reversal of 21541255501 is 10555214512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19078515625 + 2462739876 = 138125^2 + 49626^2 .

It is a cyclic number.

It is not a de Polignac number, because 21541255501 - 2¹³ = 21541247309 is a prime.

It is a super-2 number, since 2×21541255501² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21541255507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770627750 + 10770627751.

It is an arithmetic number, because the mean of its divisors is an integer number (10770627751).

Almost surely, 2^21541255501 is an apocalyptic number.

It is an amenable number.

21541255501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21541255501 is an equidigital number, since it uses as much as digits as its factorization.

21541255501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10000, while the sum is 31.

The spelling of 21541255501 in words is "twenty-one billion, five hundred forty-one million, two hundred fifty-five thousand, five hundred one".