61643220 has 96 divisors (see below), whose sum is σ = 189665280. Its totient is φ = 14889600.

The previous prime is 61643191. The next prime is 61643297. The reversal of 61643220 is 2234616.

It is a congruent number.

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, 25045 + ... + 27395.

It is an arithmetic number, because the mean of its divisors is an integer number (1975680).

Almost surely, 2^61643220 is an apocalyptic number.

61643220 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 61643220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94832640).

61643220 is an abundant number, since it is smaller than the sum of its proper divisors (128022060).

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

61643220 is a wasteful number, since it uses less digits than its factorization.

61643220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2405 (or 2403 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 61643220 is about 7851.3196343035. The cubic root of 61643220 is about 395.0285083307.

Adding to 61643220 its reverse (2234616), we get a palindrome (63877836).

The spelling of 61643220 in words is "sixty-one million, six hundred forty-three thousand, two hundred twenty".