1285556641 has 4 divisors (see below), whose sum is σ = 1341450432. Its totient is φ = 1229662852.

The previous prime is 1285556627. The next prime is 1285556647. The reversal of 1285556641 is 1466555821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1285556641 - 2⁷ = 1285556513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1285556647) 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, 27946861 + ... + 27946906.

It is an arithmetic number, because the mean of its divisors is an integer number (335362608).

Almost surely, 2^1285556641 is an apocalyptic number.

It is an amenable number.

1285556641 is a deficient number, since it is larger than the sum of its proper divisors (55893791).

1285556641 is an equidigital number, since it uses as much as digits as its factorization.

1285556641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55893790.

The product of its digits is 288000, while the sum is 43.

The square root of 1285556641 is about 35854.6599621304. The cubic root of 1285556641 is about 1087.3359290242.

It can be divided in two parts, 12855 and 56641, that added together give a palindrome (69496).

The spelling of 1285556641 in words is "one billion, two hundred eighty-five million, five hundred fifty-six thousand, six hundred forty-one".