21155612061 has 8 divisors (see below), whose sum is σ = 28213795584. Its totient is φ = 14100584960.

The previous prime is 21155612059. The next prime is 21155612077. The reversal of 21155612061 is 16021655112.

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

It is a cyclic number.

It is not a de Polignac number, because 21155612061 - 2¹ = 21155612059 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155612081) 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 7 ways as a sum of consecutive naturals, for example, 773421 + ... + 800306.

It is an arithmetic number, because the mean of its divisors is an integer number (3526724448).

Almost surely, 2^21155612061 is an apocalyptic number.

It is an amenable number.

21155612061 is a deficient number, since it is larger than the sum of its proper divisors (7058183523).

21155612061 is a wasteful number, since it uses less digits than its factorization.

21155612061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1578211.

The product of its (nonzero) digits is 3600, while the sum is 30.

The spelling of 21155612061 in words is "twenty-one billion, one hundred fifty-five million, six hundred twelve thousand, sixty-one".