61391440 has 40 divisors (see below), whose sum is σ = 155713248. Its totient is φ = 22323840.

The previous prime is 61391423. The next prime is 61391441. The reversal of 61391440 is 4419316.

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

It is a junction number, because it is equal to n+sod(n) for n = 61391399 and 61391408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61391441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34002 + ... + 35761.

Almost surely, 2^61391440 is an apocalyptic number.

It is an amenable number.

61391440 is an abundant number, since it is smaller than the sum of its proper divisors (94321808).

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

61391440 is a wasteful number, since it uses less digits than its factorization.

61391440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69787 (or 69781 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 61391440 is about 7835.2689807051. The cubic root of 61391440 is about 394.4899468032.

The spelling of 61391440 in words is "sixty-one million, three hundred ninety-one thousand, four hundred forty".