21155153551 has 4 divisors (see below), whose sum is σ = 24177318352. Its totient is φ = 18132988752.

The previous prime is 21155153483. The next prime is 21155153561. The reversal of 21155153551 is 15535155112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21155153551 - 2⁷ = 21155153423 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155153561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1511082390 + ... + 1511082403.

It is an arithmetic number, because the mean of its divisors is an integer number (6044329588).

Almost surely, 2^21155153551 is an apocalyptic number.

21155153551 is a deficient number, since it is larger than the sum of its proper divisors (3022164801).

21155153551 is an equidigital number, since it uses as much as digits as its factorization.

21155153551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3022164800.

The product of its digits is 18750, while the sum is 34.

The spelling of 21155153551 in words is "twenty-one billion, one hundred fifty-five million, one hundred fifty-three thousand, five hundred fifty-one".