737521981681 has 9 divisors (see below), whose sum is σ = 739235804619. Its totient is φ = 735812128800.

The previous prime is 737521981631. The next prime is 737521981709. The reversal of 737521981681 is 186189125737.

The square root of 737521981681 is 858791.

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., 125309628081 + 612212353600 = 353991^2 + 782440^2 .

It is not a de Polignac number, because 737521981681 - 2¹¹ = 737521979633 is a prime.

It is a super-2 number, since 2×737521981681² (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 (737521981631) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 541896441 + ... + 541897801.

Almost surely, 2^737521981681 is an apocalyptic number.

737521981681 is the 858791-st square number.

737521981681 is the 429396-th centered octagonal number.

It is an amenable number.

737521981681 is a deficient number, since it is larger than the sum of its proper divisors (1713822938).

737521981681 is an frugal number, since it uses more digits than its factorization.

With its predecessor (737521981680) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (3984).

737521981681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3984 (or 1992 counting only the distinct ones).

The product of its digits is 5080320, while the sum is 58.

The spelling of 737521981681 in words is "seven hundred thirty-seven billion, five hundred twenty-one million, nine hundred eighty-one thousand, six hundred eighty-one".