21555616231 has 8 divisors (see below), whose sum is σ = 21655677824. Its totient is φ = 21455642880.

The previous prime is 21555616211. The next prime is 21555616249. The reversal of 21555616231 is 13261655512.

It is a happy number.

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 21555616231 - 2²³ = 21547227623 is a prime.

It is a super-2 number, since 2×21555616231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21555616211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 495595 + ... + 537331.

It is an arithmetic number, because the mean of its divisors is an integer number (2706959728).

Almost surely, 2^21555616231 is an apocalyptic number.

21555616231 is a deficient number, since it is larger than the sum of its proper divisors (100061593).

21555616231 is a wasteful number, since it uses less digits than its factorization.

21555616231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44121.

The product of its digits is 54000, while the sum is 37.

The spelling of 21555616231 in words is "twenty-one billion, five hundred fifty-five million, six hundred sixteen thousand, two hundred thirty-one".