21379275787 has 4 divisors (see below), whose sum is σ = 21382495920. Its totient is φ = 21376055656.

The previous prime is 21379275781. The next prime is 21379275793. The reversal of 21379275787 is 78757297312.

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

It is an interprime number because it is at equal distance from previous prime (21379275781) and next prime (21379275793).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21379275787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21379275781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1600087 + ... + 1613392.

It is an arithmetic number, because the mean of its divisors is an integer number (5345623980).

Almost surely, 2^21379275787 is an apocalyptic number.

21379275787 is a deficient number, since it is larger than the sum of its proper divisors (3220133).

21379275787 is an equidigital number, since it uses as much as digits as its factorization.

21379275787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3220132.

The product of its digits is 10372320, while the sum is 58.

The spelling of 21379275787 in words is "twenty-one billion, three hundred seventy-nine million, two hundred seventy-five thousand, seven hundred eighty-seven".