261555456646 has 32 divisors (see below), whose sum is σ = 434216764800. Its totient is φ = 117168934080.

The previous prime is 261555456637. The next prime is 261555456709. The reversal of 261555456646 is 646654555162.

It is a super-2 number, since 2×261555456646² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

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, 571725 + ... + 921943.

It is an arithmetic number, because the mean of its divisors is an integer number (13569273900).

Almost surely, 2^261555456646 is an apocalyptic number.

261555456646 is a deficient number, since it is larger than the sum of its proper divisors (172661308154).

261555456646 is a wasteful number, since it uses less digits than its factorization.

261555456646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350724.

The product of its digits is 25920000, while the sum is 55.

It can be divided in two parts, 261555 and 456646, that added together give a triangular number (718201 = T₁₁₉₈).

The spelling of 261555456646 in words is "two hundred sixty-one billion, five hundred fifty-five million, four hundred fifty-six thousand, six hundred forty-six".