21042451055501 has 2 divisors, whose sum is σ = 21042451055502. Its totient is φ = 21042451055500.

The previous prime is 21042451055389. The next prime is 21042451055513. The reversal of 21042451055501 is 10555015424012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21007509726025 + 34941329476 = 4583395^2 + 186926^2 .

It is a cyclic number.

It is not a de Polignac number, because 21042451055501 - 2¹⁴ = 21042451039117 is a prime.

It is a super-2 number, since 2×21042451055501² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21042451055201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521225527750 + 10521225527751.

It is an arithmetic number, because the mean of its divisors is an integer number (10521225527751).

Almost surely, 2^{21042451055501} is an apocalyptic number.

It is an amenable number.

21042451055501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042451055501 is an equidigital number, since it uses as much as digits as its factorization.

21042451055501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40000, while the sum is 35.

Adding to 21042451055501 its reverse (10555015424012), we get a palindrome (31597466479513).

The spelling of 21042451055501 in words is "twenty-one trillion, forty-two billion, four hundred fifty-one million, fifty-five thousand, five hundred one".