21144155531 has 8 divisors (see below), whose sum is σ = 21729193440. Its totient is φ = 20559832128.

The previous prime is 21144155479. The next prime is 21144155533. The reversal of 21144155531 is 13555144112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21144155531 is a prime.

It is a super-2 number, since 2×21144155531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21144155533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 118346 + ... + 237263.

It is an arithmetic number, because the mean of its divisors is an integer number (2716149180).

Almost surely, 2^21144155531 is an apocalyptic number.

21144155531 is a deficient number, since it is larger than the sum of its proper divisors (585037909).

21144155531 is a wasteful number, since it uses less digits than its factorization.

21144155531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 357253.

The product of its digits is 12000, while the sum is 32.

Adding to 21144155531 its reverse (13555144112), we get a palindrome (34699299643).

The spelling of 21144155531 in words is "twenty-one billion, one hundred forty-four million, one hundred fifty-five thousand, five hundred thirty-one".