261743664 has 160 divisors (see below), whose sum is σ = 859500544. Its totient is φ = 66769920.

The previous prime is 261743663. The next prime is 261743687. The reversal of 261743664 is 466347162.

It is a happy number.

261743664 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (261743663) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 134442 + ... + 136374.

Almost surely, 2^261743664 is an apocalyptic number.

261743664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261743664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (429750272).

261743664 is an abundant number, since it is smaller than the sum of its proper divisors (597756880).

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

261743664 is a wasteful number, since it uses less digits than its factorization.

261743664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1995 (or 1989 counting only the distinct ones).

The product of its digits is 145152, while the sum is 39.

The square root of 261743664 is about 16178.4938730402. The cubic root of 261743664 is about 639.6740397416.

The spelling of 261743664 in words is "two hundred sixty-one million, seven hundred forty-three thousand, six hundred sixty-four".