21151144561 has 8 divisors (see below), whose sum is σ = 21408660000. Its totient is φ = 20893693152.

The previous prime is 21151144559. The next prime is 21151144583. The reversal of 21151144561 is 16544115112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21151144561 - 2¹ = 21151144559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21151144061) 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 7 ways as a sum of consecutive naturals, for example, 1293565 + ... + 1309813.

It is an arithmetic number, because the mean of its divisors is an integer number (2676082500).

Almost surely, 2^21151144561 is an apocalyptic number.

It is an amenable number.

21151144561 is a deficient number, since it is larger than the sum of its proper divisors (257515439).

21151144561 is a wasteful number, since it uses less digits than its factorization.

21151144561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32015.

The product of its digits is 4800, while the sum is 31.

Adding to 21151144561 its reverse (16544115112), we get a palindrome (37695259673).

The spelling of 21151144561 in words is "twenty-one billion, one hundred fifty-one million, one hundred forty-four thousand, five hundred sixty-one".