261918738 has 16 divisors (see below), whose sum is σ = 582041760. Its totient is φ = 87306228.

The previous prime is 261918703. The next prime is 261918791. The reversal of 261918738 is 837819162.

It is a junction number, because it is equal to n+sod(n) for n = 261918693 and 261918702.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2425120 + ... + 2425227.

It is an arithmetic number, because the mean of its divisors is an integer number (36377610).

Almost surely, 2^261918738 is an apocalyptic number.

261918738 is an abundant number, since it is smaller than the sum of its proper divisors (320123022).

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

261918738 is a wasteful number, since it uses less digits than its factorization.

261918738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4850358 (or 4850352 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The square root of 261918738 is about 16183.9036700050. The cubic root of 261918738 is about 639.8166287811.

The spelling of 261918738 in words is "two hundred sixty-one million, nine hundred eighteen thousand, seven hundred thirty-eight".