61809090 has 96 divisors (see below), whose sum is σ = 181725120. Its totient is φ = 13378176.

The previous prime is 61809053. The next prime is 61809091. The reversal of 61809090 is 9090816.

It is a happy number.

61809090 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

61809090 is a modest number, since divided by 9090 gives 6180 as remainder.

It is not an unprimeable number, because it can be changed into a prime (61809091) 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 47 ways as a sum of consecutive naturals, for example, 26824 + ... + 29036.

It is an arithmetic number, because the mean of its divisors is an integer number (1892970).

Almost surely, 2^61809090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61809090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90862560).

61809090 is an abundant number, since it is smaller than the sum of its proper divisors (119916030).

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

61809090 is a wasteful number, since it uses less digits than its factorization.

61809090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2256 (or 2249 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 61809090 is about 7861.8757303839. The cubic root of 61809090 is about 395.3825061487.

The spelling of 61809090 in words is "sixty-one million, eight hundred nine thousand, ninety".