61991380 has 48 divisors (see below), whose sum is σ = 145341504. Its totient is φ = 22014720.

The previous prime is 61991353. The next prime is 61991383. The reversal of 61991380 is 8319916.

61991380 = T₂₀₉ + T₂₁₀ + ... + T₇₂₄.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61991383) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6184 + ... + 12736.

It is an arithmetic number, because the mean of its divisors is an integer number (3027948).

Almost surely, 2^61991380 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61991380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72670752).

61991380 is an abundant number, since it is smaller than the sum of its proper divisors (83350124).

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

61991380 is a wasteful number, since it uses less digits than its factorization.

61991380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6616 (or 6614 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 61991380 is about 7873.4604844376. The cubic root of 61991380 is about 395.7708176310.

The spelling of 61991380 in words is "sixty-one million, nine hundred ninety-one thousand, three hundred eighty".