21155102551 has 8 divisors (see below), whose sum is σ = 23641179408. Its totient is φ = 18762840000.

The previous prime is 21155102543. The next prime is 21155102581. The reversal of 21155102551 is 15520155112.

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 21155102551 - 2³ = 21155102543 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155102581) 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, 23453100 + ... + 23454001.

It is an arithmetic number, because the mean of its divisors is an integer number (2955147426).

Almost surely, 2^21155102551 is an apocalyptic number.

21155102551 is a deficient number, since it is larger than the sum of its proper divisors (2486076857).

21155102551 is a wasteful number, since it uses less digits than its factorization.

21155102551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46907153.

The product of its (nonzero) digits is 2500, while the sum is 28.

Adding to 21155102551 its reverse (15520155112), we get a palindrome (36675257663).

The spelling of 21155102551 in words is "twenty-one billion, one hundred fifty-five million, one hundred two thousand, five hundred fifty-one".