21144235501 has 32 divisors (see below), whose sum is σ = 23926129920. Its totient is φ = 18607142400.

The previous prime is 21144235499. The next prime is 21144235531. The reversal of 21144235501 is 10553244112.

It is not a de Polignac number, because 21144235501 - 2¹ = 21144235499 is a prime.

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 21144235501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144235531) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1166931 + ... + 1184911.

It is an arithmetic number, because the mean of its divisors is an integer number (747691560).

Almost surely, 2^21144235501 is an apocalyptic number.

It is an amenable number.

21144235501 is a deficient number, since it is larger than the sum of its proper divisors (2781894419).

21144235501 is a wasteful number, since it uses less digits than its factorization.

21144235501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18117.

The product of its (nonzero) digits is 4800, while the sum is 28.

Adding to 21144235501 its reverse (10553244112), we get a palindrome (31697479613).

The spelling of 21144235501 in words is "twenty-one billion, one hundred forty-four million, two hundred thirty-five thousand, five hundred one".