1281901748521 has 9 divisors (see below), whose sum is σ = 1284691909431. Its totient is φ = 1279117641672.

The previous prime is 1281901748509. The next prime is 1281901748527. The reversal of 1281901748521 is 1258471091821.

The square root of 1281901748521 is 1132211.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 4178976025 + 1277722772496 = 64645^2 + 1130364^2 .

It is not a de Polignac number, because 1281901748521 - 2²³ = 1281893359913 is a prime.

It is a super-2 number, since 2×1281901748521² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1281901748527) 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 in 8 ways as a sum of consecutive naturals, for example, 694044420 + ... + 694046266.

Almost surely, 2^{1281901748521} is an apocalyptic number.

1281901748521 is the 1132211-st square number.

1281901748521 is the 566106-th centered octagonal number.

It is an amenable number.

1281901748521 is a deficient number, since it is larger than the sum of its proper divisors (2790160910).

1281901748521 is an frugal number, since it uses more digits than its factorization.

1281901748521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4920 (or 2460 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 49.

Multiplying 1281901748521 by its sum of digits (49), we get a square (62813185677529 = 7925477²).

The spelling of 1281901748521 in words is "one trillion, two hundred eighty-one billion, nine hundred one million, seven hundred forty-eight thousand, five hundred twenty-one".