261664746 has 64 divisors (see below), whose sum is σ = 614127360. Its totient is φ = 72783360.

The previous prime is 261664727. The next prime is 261664759. The reversal of 261664746 is 647466162.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 261664698 and 261664707.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 278790 + ... + 279726.

It is an arithmetic number, because the mean of its divisors is an integer number (9595740).

Almost surely, 2^261664746 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261664746, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (307063680).

261664746 is an abundant number, since it is smaller than the sum of its proper divisors (352462614).

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

261664746 is a wasteful number, since it uses less digits than its factorization.

261664746 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1119.

The product of its digits is 290304, while the sum is 42.

The square root of 261664746 is about 16176.0547105900. The cubic root of 261664746 is about 639.6097441766.

The spelling of 261664746 in words is "two hundred sixty-one million, six hundred sixty-four thousand, seven hundred forty-six".