1261865385 has 80 divisors (see below), whose sum is σ = 2547528192. Its totient is φ = 592012800.

The previous prime is 1261865383. The next prime is 1261865387. The reversal of 1261865385 is 5835681621.

1261865385 is a `hidden beast` number, since 1 + 261 + 8 + 6 + 5 + 385 = 666.

It is an interprime number because it is at equal distance from previous prime (1261865383) and next prime (1261865387).

It is not a de Polignac number, because 1261865385 - 2¹ = 1261865383 is a prime.

It is a super-2 number, since 2×1261865385² = 3184608499722396450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 1261865385.

It is not an unprimeable number, because it can be changed into a prime (1261865383) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 133537 + ... + 142673.

Almost surely, 2^1261865385 is an apocalyptic number.

1261865385 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1261865385 is an abundant number, since it is smaller than the sum of its proper divisors (1285662807).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1261865385 is a wasteful number, since it uses less digits than its factorization.

1261865385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9196 (or 9187 counting only the distinct ones).

The product of its digits is 345600, while the sum is 45.

The square root of 1261865385 is about 35522.7446152462. The cubic root of 1261865385 is about 1080.6150431945.

The spelling of 1261865385 in words is "one billion, two hundred sixty-one million, eight hundred sixty-five thousand, three hundred eighty-five".