61644240 has 280 divisors, whose sum is σ = 247210368. Its totient is φ = 13996800.

The previous prime is 61644223. The next prime is 61644263. The reversal of 61644240 is 4244616.

61644240 is a `hidden beast` number, since 616 + 4 + 4 + 2 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (280).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 408165 + ... + 408315.

Almost surely, 2^61644240 is an apocalyptic number.

61644240 is a gapful number since it is divisible by the number (60) 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 61644240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123605184).

61644240 is an abundant number, since it is smaller than the sum of its proper divisors (185566128).

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

61644240 is a wasteful number, since it uses less digits than its factorization.

61644240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189 (or 168 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 61644240 is about 7851.3845912680. The cubic root of 61644240 is about 395.0306871421.

Adding to 61644240 its reverse (4244616), we get a palindrome (65888856).

It can be divided in two parts, 6164 and 4240, that added together give a square (10404 = 102²).

The spelling of 61644240 in words is "sixty-one million, six hundred forty-four thousand, two hundred forty".