21655536123 has 24 divisors (see below), whose sum is σ = 31453325568. Its totient is φ = 13246632672.

The previous prime is 21655536073. The next prime is 21655536143. The reversal of 21655536123 is 32163555612.

It is not a de Polignac number, because 21655536123 - 2¹² = 21655532027 is a prime.

It is a super-2 number, since 2×21655536123² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21655536143) 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 23 ways as a sum of consecutive naturals, for example, 43215 + ... + 212552.

It is an arithmetic number, because the mean of its divisors is an integer number (1310555232).

Almost surely, 2^21655536123 is an apocalyptic number.

21655536123 is a deficient number, since it is larger than the sum of its proper divisors (9797789445).

21655536123 is a wasteful number, since it uses less digits than its factorization.

21655536123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255963 (or 255950 counting only the distinct ones).

The product of its digits is 162000, while the sum is 39.

The spelling of 21655536123 in words is "twenty-one billion, six hundred fifty-five million, five hundred thirty-six thousand, one hundred twenty-three".