21184781151 has 4 divisors (see below), whose sum is σ = 28246374872. Its totient is φ = 14123187432.

The previous prime is 21184781131. The next prime is 21184781153. The reversal of 21184781151 is 15118748112.

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

It is a de Polignac number, because none of the positive numbers 2^k-21184781151 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 (21184781153) 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, 3530796856 + ... + 3530796861.

It is an arithmetic number, because the mean of its divisors is an integer number (7061593718).

Almost surely, 2^21184781151 is an apocalyptic number.

21184781151 is a deficient number, since it is larger than the sum of its proper divisors (7061593721).

21184781151 is an equidigital number, since it uses as much as digits as its factorization.

21184781151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7061593720.

The product of its digits is 17920, while the sum is 39.

The spelling of 21184781151 in words is "twenty-one billion, one hundred eighty-four million, seven hundred eighty-one thousand, one hundred fifty-one".