537721957781 has 2 divisors, whose sum is σ = 537721957782. Its totient is φ = 537721957780.

The previous prime is 537721957777. The next prime is 537721957813. The reversal of 537721957781 is 187759127735.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 359778034225 + 177943923556 = 599815^2 + 421834^2 .

It is a cyclic number.

It is not a de Polignac number, because 537721957781 - 2² = 537721957777 is a prime.

It is a super-2 number, since 2×537721957781² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (537721957481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 268860978890 + 268860978891.

It is an arithmetic number, because the mean of its divisors is an integer number (268860978891).

Almost surely, 2^537721957781 is an apocalyptic number.

It is an amenable number.

537721957781 is a deficient number, since it is larger than the sum of its proper divisors (1).

537721957781 is an equidigital number, since it uses as much as digits as its factorization.

537721957781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25930800, while the sum is 62.

The spelling of 537721957781 in words is "five hundred thirty-seven billion, seven hundred twenty-one million, nine hundred fifty-seven thousand, seven hundred eighty-one".