12561221490 has 64 divisors (see below), whose sum is σ = 30960268416. Its totient is φ = 3259855872.

The previous prime is 12561221489. The next prime is 12561221503. The reversal of 12561221490 is 9412216521.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 339754 + ... + 374906.

It is an arithmetic number, because the mean of its divisors is an integer number (483754194).

Almost surely, 2^12561221490 is an apocalyptic number.

12561221490 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 12561221490, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15480134208).

12561221490 is an abundant number, since it is smaller than the sum of its proper divisors (18399046926).

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

12561221490 is a wasteful number, since it uses less digits than its factorization.

12561221490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35483.

The product of its (nonzero) digits is 8640, while the sum is 33.

The spelling of 12561221490 in words is "twelve billion, five hundred sixty-one million, two hundred twenty-one thousand, four hundred ninety".