12021659978 has 4 divisors (see below), whose sum is σ = 18032489970. Its totient is φ = 6010829988.

The previous prime is 12021659977. The next prime is 12021660011. The reversal of 12021659978 is 87995612021.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87995612021 = 29 ⋅3034331449.

It can be written as a sum of positive squares in only one way, i.e., 7899121129 + 4122538849 = 88877^2 + 64207^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12021659977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3005414993 + ... + 3005414996.

Almost surely, 2^12021659978 is an apocalyptic number.

12021659978 is a deficient number, since it is larger than the sum of its proper divisors (6010829992).

12021659978 is an equidigital number, since it uses as much as digits as its factorization.

12021659978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6010829991.

The product of its (nonzero) digits is 544320, while the sum is 50.

The spelling of 12021659978 in words is "twelve billion, twenty-one million, six hundred fifty-nine thousand, nine hundred seventy-eight".