61617720 has 32 divisors (see below), whose sum is σ = 184853520. Its totient is φ = 16431360.

The previous prime is 61617719. The next prime is 61617737. The reversal of 61617720 is 2771616.

It is a happy number.

61617720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

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 7 ways as a sum of consecutive naturals, for example, 256621 + ... + 256860.

Almost surely, 2^61617720 is an apocalyptic number.

61617720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

61617720 is an abundant number, since it is smaller than the sum of its proper divisors (123235800).

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

61617720 is a wasteful number, since it uses less digits than its factorization.

61617720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 513495 (or 513491 counting only the distinct ones).

The product of its (nonzero) digits is 3528, while the sum is 30.

The square root of 61617720 is about 7849.6955354969. The cubic root of 61617720 is about 394.9740302319.

It can be divided in two parts, 616 and 17720, that added together give a triangular number (18336 = T₁₉₁).

The spelling of 61617720 in words is "sixty-one million, six hundred seventeen thousand, seven hundred twenty".