21108315501 has 48 divisors (see below), whose sum is σ = 39175416000. Its totient is φ = 11134047456.

The previous prime is 21108315491. The next prime is 21108315509. The reversal of 21108315501 is 10551380112.

21108315501 is a `hidden beast` number, since 2 + 1 + 108 + 3 + 1 + 550 + 1 = 666.

It is not a de Polignac number, because 21108315501 - 2⁹ = 21108314989 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21108315509) 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 47 ways as a sum of consecutive naturals, for example, 596451 + ... + 630848.

It is an arithmetic number, because the mean of its divisors is an integer number (816154500).

Almost surely, 2^21108315501 is an apocalyptic number.

21108315501 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21108315501 is a deficient number, since it is larger than the sum of its proper divisors (18067100499).

21108315501 is a wasteful number, since it uses less digits than its factorization.

21108315501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1227335 (or 1227322 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 27.

Adding to 21108315501 its reverse (10551380112), we get a palindrome (31659695613).

The spelling of 21108315501 in words is "twenty-one billion, one hundred eight million, three hundred fifteen thousand, five hundred one".