1261826778 has 8 divisors (see below), whose sum is σ = 2523653568. Its totient is φ = 420608924.

The previous prime is 1261826749. The next prime is 1261826807. The reversal of 1261826778 is 8776281621.

It is an interprime number because it is at equal distance from previous prime (1261826749) and next prime (1261826807).

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

1261826778 is an admirable number.

It is a super-2 number, since 2×1261826778² = 3184413635355722568, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105152226 + ... + 105152237.

It is an arithmetic number, because the mean of its divisors is an integer number (315456696).

Almost surely, 2^1261826778 is an apocalyptic number.

1261826778 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

1261826778 is a wasteful number, since it uses less digits than its factorization.

1261826778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210304468.

The product of its digits is 451584, while the sum is 48.

The square root of 1261826778 is about 35522.2011986870. The cubic root of 1261826778 is about 1080.6040225445.

The spelling of 1261826778 in words is "one billion, two hundred sixty-one million, eight hundred twenty-six thousand, seven hundred seventy-eight".