21111002547 has 4 divisors (see below), whose sum is σ = 28148003400. Its totient is φ = 14074001696.

The previous prime is 21111002531. The next prime is 21111002557. The reversal of 21111002547 is 74520011112.

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 21111002547 - 2⁴ = 21111002531 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21111002557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3518500422 + ... + 3518500427.

It is an arithmetic number, because the mean of its divisors is an integer number (7037000850).

Almost surely, 2^21111002547 is an apocalyptic number.

21111002547 is a deficient number, since it is larger than the sum of its proper divisors (7037000853).

21111002547 is an equidigital number, since it uses as much as digits as its factorization.

21111002547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7037000852.

The product of its (nonzero) digits is 560, while the sum is 24.

Adding to 21111002547 its reverse (74520011112), we get a palindrome (95631013659).

The spelling of 21111002547 in words is "twenty-one billion, one hundred eleven million, two thousand, five hundred forty-seven".