21115252551 has 8 divisors (see below), whose sum is σ = 28154753280. Its totient is φ = 14076293432.

The previous prime is 21115252493. The next prime is 21115252573. The reversal of 21115252551 is 15525251112.

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 21115252551 - 2²² = 21111058247 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115252751) 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, 33471 + ... + 208208.

It is an arithmetic number, because the mean of its divisors is an integer number (3519344160).

Almost surely, 2^21115252551 is an apocalyptic number.

21115252551 is a deficient number, since it is larger than the sum of its proper divisors (7039500729).

21115252551 is a wasteful number, since it uses less digits than its factorization.

21115252551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270805.

The product of its digits is 5000, while the sum is 30.

The spelling of 21115252551 in words is "twenty-one billion, one hundred fifteen million, two hundred fifty-two thousand, five hundred fifty-one".