61661664 has 72 divisors (see below), whose sum is σ = 176255352. Its totient is φ = 20448000.

The previous prime is 61661653. The next prime is 61661681. The reversal of 61661664 is 46616616.

61661664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71862 + ... + 72714.

It is an arithmetic number, because the mean of its divisors is an integer number (2447991).

Almost surely, 2^61661664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61661664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88127676).

61661664 is an abundant number, since it is smaller than the sum of its proper divisors (114593688).

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

61661664 is a wasteful number, since it uses less digits than its factorization.

61661664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1120 (or 1109 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 61661664 is about 7852.4941260723. The cubic root of 61661664 is about 395.0679026565.

The spelling of 61661664 in words is "sixty-one million, six hundred sixty-one thousand, six hundred sixty-four".