1261908978 has 32 divisors (see below), whose sum is σ = 2898167040. Its totient is φ = 362270160.

The previous prime is 1261908919. The next prime is 1261909039. The reversal of 1261908978 is 8798091621.

It is a self number, because there is not a number n which added to its sum of digits gives 1261908978.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 501900 + ... + 504407.

It is an arithmetic number, because the mean of its divisors is an integer number (90567720).

Almost surely, 2^1261908978 is an apocalyptic number.

1261908978 is an abundant number, since it is smaller than the sum of its proper divisors (1636258062).

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

1261908978 is a wasteful number, since it uses less digits than its factorization.

1261908978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1006342.

The product of its (nonzero) digits is 435456, while the sum is 51.

The square root of 1261908978 is about 35523.3582027375. The cubic root of 1261908978 is about 1080.6274868645.

The spelling of 1261908978 in words is "one billion, two hundred sixty-one million, nine hundred eight thousand, nine hundred seventy-eight".