61643988 has 36 divisors (see below), whose sum is σ = 178083360. Its totient is φ = 17612496.

The previous prime is 61643987. The next prime is 61644001. The reversal of 61643988 is 88934616.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61643987) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 122058 + ... + 122561.

It is an arithmetic number, because the mean of its divisors is an integer number (4946760).

Almost surely, 2^61643988 is an apocalyptic number.

It is an amenable number.

61643988 is an abundant number, since it is smaller than the sum of its proper divisors (116439372).

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

61643988 is a wasteful number, since it uses less digits than its factorization.

61643988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244636 (or 244631 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The square root of 61643988 is about 7851.3685431267. The cubic root of 61643988 is about 395.0301488498.

The spelling of 61643988 in words is "sixty-one million, six hundred forty-three thousand, nine hundred eighty-eight".