1223653791581 has 4 divisors (see below), whose sum is σ = 1317781006332. Its totient is φ = 1129526576832.

The previous prime is 1223653791557. The next prime is 1223653791593. The reversal of 1223653791581 is 1851973563221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 60579976900 + 1163073814681 = 246130^2 + 1078459^2 .

It is a cyclic number.

It is not a de Polignac number, because 1223653791581 - 2¹⁸ = 1223653529437 is a prime.

It is a super-2 number, since 2×1223653791581² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1223653791881) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47063607356 + ... + 47063607381.

It is an arithmetic number, because the mean of its divisors is an integer number (329445251583).

Almost surely, 2^{1223653791581} is an apocalyptic number.

It is an amenable number.

1223653791581 is a deficient number, since it is larger than the sum of its proper divisors (94127214751).

1223653791581 is an equidigital number, since it uses as much as digits as its factorization.

1223653791581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94127214750.

The product of its digits is 2721600, while the sum is 53.

The spelling of 1223653791581 in words is "one trillion, two hundred twenty-three billion, six hundred fifty-three million, seven hundred ninety-one thousand, five hundred eighty-one".