28490401681 has 9 divisors (see below), whose sum is σ = 33143270331. Its totient is φ = 24419331552.

The previous prime is 28490401679. The next prime is 28490401721. The reversal of 28490401681 is 18610409482.

The square root of 28490401681 is 168791.

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., 19006758225 + 9483643456 = 137865^2 + 97384^2 .

It is not a de Polignac number, because 28490401681 - 2¹ = 28490401679 is a prime.

It is a super-2 number, since 2×28490401681² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28490401631) 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, 1169481 + ... + 1193593.

Almost surely, 2^28490401681 is an apocalyptic number.

28490401681 is the 168791-st square number.

28490401681 is the 84396-th centered octagonal number.

It is an amenable number.

28490401681 is a deficient number, since it is larger than the sum of its proper divisors (4652868650).

28490401681 is an frugal number, since it uses more digits than its factorization.

28490401681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48240 (or 24120 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 43.

The spelling of 28490401681 in words is "twenty-eight billion, four hundred ninety million, four hundred one thousand, six hundred eighty-one".