61561620 has 144 divisors (see below), whose sum is σ = 198132480. Its totient is φ = 16039296.

The previous prime is 61561613. The next prime is 61561631. The reversal of 61561620 is 2616516.

It is a happy number.

It is a super-3 number, since 3×61561620³ (a number of 24 digits) contains 333 as substring.

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 47 ways as a sum of consecutive naturals, for example, 257461 + ... + 257699.

It is an arithmetic number, because the mean of its divisors is an integer number (1375920).

Almost surely, 2^61561620 is an apocalyptic number.

61561620 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 61561620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99066240).

61561620 is an abundant number, since it is smaller than the sum of its proper divisors (136570860).

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

61561620 is a wasteful number, since it uses less digits than its factorization.

61561620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316 (or 302 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 61561620 is about 7846.1213347743. The cubic root of 61561620 is about 394.8541254864.

It can be divided in two parts, 6156 and 1620, that added together give a 5-th power (7776 = 6⁵).

The spelling of 61561620 in words is "sixty-one million, five hundred sixty-one thousand, six hundred twenty".