12521343978 has 384 divisors, whose sum is σ = 34871316480. Its totient is φ = 3193827840.

The previous prime is 12521343917. The next prime is 12521343979. The reversal of 12521343978 is 87934312521.

It is a happy number.

12521343978 is a `hidden beast` number, since 1 + 2 + 521 + 34 + 3 + 97 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (12521343979) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 150859525 + ... + 150859607.

It is an arithmetic number, because the mean of its divisors is an integer number (90810720).

Almost surely, 2^12521343978 is an apocalyptic number.

12521343978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 12521343978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17435658240).

12521343978 is an abundant number, since it is smaller than the sum of its proper divisors (22349972502).

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

12521343978 is a wasteful number, since it uses less digits than its factorization.

12521343978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234 (or 231 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The spelling of 12521343978 in words is "twelve billion, five hundred twenty-one million, three hundred forty-three thousand, nine hundred seventy-eight".