61655440 has 80 divisors (see below), whose sum is σ = 178738560. Its totient is φ = 19215360.

The previous prime is 61655417. The next prime is 61655441. The reversal of 61655440 is 4455616.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (61655441) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1156 + ... + 11164.

It is an arithmetic number, because the mean of its divisors is an integer number (2234232).

Almost surely, 2^61655440 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 61655440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89369280).

61655440 is an abundant number, since it is smaller than the sum of its proper divisors (117083120).

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

61655440 is a wasteful number, since it uses less digits than its factorization.

61655440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10040 (or 10034 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 31.

The square root of 61655440 is about 7852.0978088661. The cubic root of 61655440 is about 395.0546097653.

The spelling of 61655440 in words is "sixty-one million, six hundred fifty-five thousand, four hundred forty".