1281640781 has 8 divisors (see below), whose sum is σ = 1324425984. Its totient is φ = 1238945760.

The previous prime is 1281640739. The next prime is 1281640783. The reversal of 1281640781 is 1870461821.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1281640781 - 2¹⁴ = 1281624397 is a prime.

It is a super-2 number, since 2×1281640781² = 3285206183044579922, which 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 (1281640783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6986 + ... + 51108.

It is an arithmetic number, because the mean of its divisors is an integer number (165553248).

Almost surely, 2^1281640781 is an apocalyptic number.

It is an amenable number.

1281640781 is a deficient number, since it is larger than the sum of its proper divisors (42785203).

1281640781 is an equidigital number, since it uses as much as digits as its factorization.

1281640781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45091.

The product of its (nonzero) digits is 21504, while the sum is 38.

The square root of 1281640781 is about 35800.0109078196. The cubic root of 1281640781 is about 1086.2307823849.

The spelling of 1281640781 in words is "one billion, two hundred eighty-one million, six hundred forty thousand, seven hundred eighty-one".