61551440 has 40 divisors (see below), whose sum is σ = 145464648. Its totient is φ = 24215040.

The previous prime is 61551437. The next prime is 61551449. The reversal of 61551440 is 4415516.

61551440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 23104 + 61528336 = 152^2 + 7844^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61551449) by changing a digit.

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, 1427 + ... + 11186.

Almost surely, 2^61551440 is an apocalyptic number.

It is an amenable number.

61551440 is an abundant number, since it is smaller than the sum of its proper divisors (83913208).

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

61551440 is a wasteful number, since it uses less digits than its factorization.

61551440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12687 (or 12681 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 61551440 is about 7845.4725797749. The cubic root of 61551440 is about 394.8323595626.

Adding to 61551440 its reverse (4415516), we get a palindrome (65966956).

The spelling of 61551440 in words is "sixty-one million, five hundred fifty-one thousand, four hundred forty".