1285815861 has 48 divisors (see below), whose sum is σ = 2201671680. Its totient is φ = 714420000.

The previous prime is 1285815857. The next prime is 1285815901. The reversal of 1285815861 is 1685185821.

1285815861 is a `hidden beast` number, since 1 + 2 + 8 + 581 + 5 + 8 + 61 = 666.

It is not a de Polignac number, because 1285815861 - 2² = 1285815857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1285815761) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 47286 + ... + 69336.

It is an arithmetic number, because the mean of its divisors is an integer number (45868160).

Almost surely, 2^1285815861 is an apocalyptic number.

1285815861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1285815861 is a deficient number, since it is larger than the sum of its proper divisors (915855819).

1285815861 is a wasteful number, since it uses less digits than its factorization.

1285815861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22118 (or 22115 counting only the distinct ones).

The product of its digits is 153600, while the sum is 45.

The square root of 1285815861 is about 35858.2746517453. The cubic root of 1285815861 is about 1087.4090076860.

The spelling of 1285815861 in words is "one billion, two hundred eighty-five million, eight hundred fifteen thousand, eight hundred sixty-one".