21151145521 has 4 divisors (see below), whose sum is σ = 23073976944. Its totient is φ = 19228314100.

The previous prime is 21151145443. The next prime is 21151145567. The reversal of 21151145521 is 12554115112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21151145521 - 2⁹ = 21151145009 is a prime.

It is a super-2 number, since 2×21151145521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21151145521.

It is not an unprimeable number, because it can be changed into a prime (21151146521) 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, 961415695 + ... + 961415716.

It is an arithmetic number, because the mean of its divisors is an integer number (5768494236).

Almost surely, 2^21151145521 is an apocalyptic number.

It is an amenable number.

21151145521 is a deficient number, since it is larger than the sum of its proper divisors (1922831423).

21151145521 is a wasteful number, since it uses less digits than its factorization.

21151145521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1922831422.

The product of its digits is 2000, while the sum is 28.

The spelling of 21151145521 in words is "twenty-one billion, one hundred fifty-one million, one hundred forty-five thousand, five hundred twenty-one".