21019845687 has 8 divisors (see below), whose sum is σ = 29675076336. Its totient is φ = 13188922752.

The previous prime is 21019845661. The next prime is 21019845727. The reversal of 21019845687 is 78654891012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21019845687 - 2¹⁰ = 21019844663 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51), and also a Moran number because the ratio is a prime number: 412153837 = 21019845687 / (2 + 1 + 0 + 1 + 9 + 8 + 4 + 5 + 6 + 8 + 7).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21019845487) 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 7 ways as a sum of consecutive naturals, for example, 206076868 + ... + 206076969.

It is an arithmetic number, because the mean of its divisors is an integer number (3709384542).

Almost surely, 2^21019845687 is an apocalyptic number.

21019845687 is a deficient number, since it is larger than the sum of its proper divisors (8655230649).

21019845687 is a wasteful number, since it uses less digits than its factorization.

21019845687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412153857.

The product of its (nonzero) digits is 967680, while the sum is 51.

The spelling of 21019845687 in words is "twenty-one billion, nineteen million, eight hundred forty-five thousand, six hundred eighty-seven".