12391491420 has 648 divisors, whose sum is σ = 50962150512. Its totient is φ = 2419845120.

The previous prime is 12391491419. The next prime is 12391491433. The reversal of 12391491420 is 2419419321.

12391491420 is a `hidden beast` number, since 123 + 9 + 1 + 491 + 42 + 0 = 666.

It is a super-2 number, since 2×12391491420² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 215 ways as a sum of consecutive naturals, for example, 18142399 + ... + 18143081.

It is an arithmetic number, because the mean of its divisors is an integer number (78645294).

Almost surely, 2^12391491420 is an apocalyptic number.

12391491420 is a gapful number since it is divisible by the number (10) 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 12391491420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25481075256).

12391491420 is an abundant number, since it is smaller than the sum of its proper divisors (38570659092).

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

12391491420 is a wasteful number, since it uses less digits than its factorization.

12391491420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 751 (or 728 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The spelling of 12391491420 in words is "twelve billion, three hundred ninety-one million, four hundred ninety-one thousand, four hundred twenty".