12156021551 has 4 divisors (see below), whose sum is σ = 12484562712. Its totient is φ = 11827480392.

The previous prime is 12156021529. The next prime is 12156021601. The reversal of 12156021551 is 15512065121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15512065121 = 7 ⋅2216009303.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12156021551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12156021511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164270525 + ... + 164270598.

It is an arithmetic number, because the mean of its divisors is an integer number (3121140678).

Almost surely, 2^12156021551 is an apocalyptic number.

12156021551 is a deficient number, since it is larger than the sum of its proper divisors (328541161).

12156021551 is an equidigital number, since it uses as much as digits as its factorization.

12156021551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328541160.

The product of its (nonzero) digits is 3000, while the sum is 29.

Adding to 12156021551 its reverse (15512065121), we get a palindrome (27668086672).

The spelling of 12156021551 in words is "twelve billion, one hundred fifty-six million, twenty-one thousand, five hundred fifty-one".