21148791 has 4 divisors (see below), whose sum is σ = 28198392. Its totient is φ = 14099192.

The previous prime is 21148783. The next prime is 21148807. The reversal of 21148791 is 19784112.

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 21148791 - 2³ = 21148783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21143791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3524796 + ... + 3524801.

It is an arithmetic number, because the mean of its divisors is an integer number (7049598).

Almost surely, 2^21148791 is an apocalyptic number.

21148791 is a deficient number, since it is larger than the sum of its proper divisors (7049601).

21148791 is an equidigital number, since it uses as much as digits as its factorization.

21148791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7049600.

The product of its digits is 4032, while the sum is 33.

The square root of 21148791 is about 4598.7814690416. The cubic root of 21148791 is about 276.5424769633.

The spelling of 21148791 in words is "twenty-one million, one hundred forty-eight thousand, seven hundred ninety-one".