1351661681 has 4 divisors (see below), whose sum is σ = 1354594164. Its totient is φ = 1348729200.

The previous prime is 1351661671. The next prime is 1351661713. The reversal of 1351661681 is 1861661531.

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 998560000 + 353101681 = 31600^2 + 18791^2 .

It is a cyclic number.

It is not a de Polignac number, because 1351661681 - 2⁶ = 1351661617 is a prime.

It is a super-2 number, since 2×1351661681² = 3653978599767491522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1351661611) 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, 1465550 + ... + 1466471.

It is an arithmetic number, because the mean of its divisors is an integer number (338648541).

Almost surely, 2^1351661681 is an apocalyptic number.

It is an amenable number.

1351661681 is a deficient number, since it is larger than the sum of its proper divisors (2932483).

1351661681 is an equidigital number, since it uses as much as digits as its factorization.

1351661681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2932482.

The product of its digits is 25920, while the sum is 38.

The square root of 1351661681 is about 36764.9518019540. The cubic root of 1351661681 is about 1105.6627218280.

The spelling of 1351661681 in words is "one billion, three hundred fifty-one million, six hundred sixty-one thousand, six hundred eighty-one".