61309440 has 160 divisors (see below), whose sum is σ = 218021760. Its totient is φ = 16330752.

The previous prime is 61309433. The next prime is 61309471. The reversal of 61309440 is 4490316.

61309440 is a `hidden beast` number, since 613 + 0 + 9 + 4 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (160).

It is a super-2 number, since 2×61309440² = 7517694866227200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68677 + ... + 69563.

It is an arithmetic number, because the mean of its divisors is an integer number (1362636).

Almost surely, 2^61309440 is an apocalyptic number.

61309440 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 61309440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109010880).

61309440 is an abundant number, since it is smaller than the sum of its proper divisors (156712320).

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

61309440 is an equidigital number, since it uses as much as digits as its factorization.

61309440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 919 (or 897 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 61309440 is about 7830.0344826827. The cubic root of 61309440 is about 394.3142296417.

Adding to 61309440 its reverse (4490316), we get a palindrome (65799756).

The spelling of 61309440 in words is "sixty-one million, three hundred nine thousand, four hundred forty".