21606135232551 has 16 divisors (see below), whose sum is σ = 29516802010080. Its totient is φ = 14049921761280.

The previous prime is 21606135232543. The next prime is 21606135232553. The reversal of 21606135232551 is 15523253160612.

It is not a de Polignac number, because 21606135232551 - 2³ = 21606135232543 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606135232553) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17197786 + ... + 18411303.

It is an arithmetic number, because the mean of its divisors is an integer number (1844800125630).

Almost surely, 2^{21606135232551} is an apocalyptic number.

21606135232551 is a deficient number, since it is larger than the sum of its proper divisors (7910666777529).

21606135232551 is a wasteful number, since it uses less digits than its factorization.

21606135232551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35614066.

The product of its (nonzero) digits is 324000, while the sum is 42.

The spelling of 21606135232551 in words is "twenty-one trillion, six hundred six billion, one hundred thirty-five million, two hundred thirty-two thousand, five hundred fifty-one".