2561251786 has 4 divisors (see below), whose sum is σ = 3841877682. Its totient is φ = 1280625892.

The previous prime is 2561251757. The next prime is 2561251787. The reversal of 2561251786 is 6871521652.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1443620025 + 1117631761 = 37995^2 + 33431^2 .

It is a super-2 number, since 2×2561251786² = 13120021422576379592, which contains 22 as substring.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (2561251787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 640312945 + ... + 640312948.

Almost surely, 2^2561251786 is an apocalyptic number.

2561251786 is a deficient number, since it is larger than the sum of its proper divisors (1280625896).

2561251786 is a wasteful number, since it uses less digits than its factorization.

2561251786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280625895.

The product of its digits is 201600, while the sum is 43.

The square root of 2561251786 is about 50608.8113474324. The cubic root of 2561251786 is about 1368.2036922533.

The spelling of 2561251786 in words is "two billion, five hundred sixty-one million, two hundred fifty-one thousand, seven hundred eighty-six".