61991040 has 128 divisors (see below), whose sum is σ = 200491200. Its totient is φ = 16289792.

The previous prime is 61991029. The next prime is 61991099. The reversal of 61991040 is 4019916.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 61990989 and 61991007.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 159166 + ... + 159554.

Almost surely, 2^61991040 is an apocalyptic number.

61991040 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 61991040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100245600).

61991040 is an abundant number, since it is smaller than the sum of its proper divisors (138500160).

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

61991040 is a wasteful number, since it uses less digits than its factorization.

61991040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494 (or 482 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 61991040 is about 7873.4388928854. The cubic root of 61991040 is about 395.7700940770.

The spelling of 61991040 in words is "sixty-one million, nine hundred ninety-one thousand, forty".