61515540 has 72 divisors (see below), whose sum is σ = 196428960. Its totient is φ = 15539904.

The previous prime is 61515523. The next prime is 61515541. The reversal of 61515540 is 4551516.

It is a happy number.

61515540 is a `hidden beast` number, since 61 + 51 + 554 + 0 = 666.

61515540 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×61515540² = 7568323322983200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61515541) 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 23 ways as a sum of consecutive naturals, for example, 5574 + ... + 12413.

It is an arithmetic number, because the mean of its divisors is an integer number (2728180).

Almost surely, 2^61515540 is an apocalyptic number.

61515540 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

61515540 is an abundant number, since it is smaller than the sum of its proper divisors (134913420).

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

61515540 is a wasteful number, since it uses less digits than its factorization.

61515540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18021 (or 18016 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The square root of 61515540 is about 7843.1843023099. The cubic root of 61515540 is about 394.7555823805.

The spelling of 61515540 in words is "sixty-one million, five hundred fifteen thousand, five hundred forty".