61131840 has 224 divisors, whose sum is σ = 242279424. Its totient is φ = 12687360.

The previous prime is 61131809. The next prime is 61131841. The reversal of 61131840 is 4813116.

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 61131840.

It is not an unprimeable number, because it can be changed into a prime (61131841) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 73507 + ... + 74333.

Almost surely, 2^61131840 is an apocalyptic number.

61131840 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 61131840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121139712).

61131840 is an abundant number, since it is smaller than the sum of its proper divisors (181147584).

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

61131840 is a wasteful number, since it uses less digits than its factorization.

61131840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 865 (or 855 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 61131840 is about 7818.6853114830. The cubic root of 61131840 is about 393.9331141238.

Adding to 61131840 its reverse (4813116), we get a palindrome (65944956).

The spelling of 61131840 in words is "sixty-one million, one hundred thirty-one thousand, eight hundred forty".