21507555521741 has 2 divisors, whose sum is σ = 21507555521742. Its totient is φ = 21507555521740.

The previous prime is 21507555521681. The next prime is 21507555521797. The reversal of 21507555521741 is 14712555570512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10973285634025 + 10534269887716 = 3312595^2 + 3245654^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21507555521741 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21507555521741.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21507555521041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753777760870 + 10753777760871.

It is an arithmetic number, because the mean of its divisors is an integer number (10753777760871).

Almost surely, 2^{21507555521741} is an apocalyptic number.

It is an amenable number.

21507555521741 is a deficient number, since it is larger than the sum of its proper divisors (1).

21507555521741 is an equidigital number, since it uses as much as digits as its factorization.

21507555521741 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2450000, while the sum is 50.

The spelling of 21507555521741 in words is "twenty-one trillion, five hundred seven billion, five hundred fifty-five million, five hundred twenty-one thousand, seven hundred forty-one".