21981152615 has 4 divisors (see below), whose sum is σ = 26377383144. Its totient is φ = 17584922088.

The previous prime is 21981152603. The next prime is 21981152617. The reversal of 21981152615 is 51625118912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21981152615 - 2¹⁸ = 21980890471 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 (21981152617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2198115257 + ... + 2198115266.

It is an arithmetic number, because the mean of its divisors is an integer number (6594345786).

Almost surely, 2^21981152615 is an apocalyptic number.

21981152615 is a deficient number, since it is larger than the sum of its proper divisors (4396230529).

21981152615 is an equidigital number, since it uses as much as digits as its factorization.

21981152615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4396230528.

The product of its digits is 43200, while the sum is 41.

The spelling of 21981152615 in words is "twenty-one billion, nine hundred eighty-one million, one hundred fifty-two thousand, six hundred fifteen".