21787421085 has 96 divisors (see below), whose sum is σ = 41463871488. Its totient is φ = 10535546880.

The previous prime is 21787421077. The next prime is 21787421093. The reversal of 21787421085 is 58012478712.

21787421085 is a `hidden beast` number, since 217 + 8 + 7 + 421 + 0 + 8 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (21787421077) and next prime (21787421093).

It is not a de Polignac number, because 21787421085 - 2³ = 21787421077 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21787421085.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 5523624 + ... + 5527566.

It is an arithmetic number, because the mean of its divisors is an integer number (431915328).

Almost surely, 2^21787421085 is an apocalyptic number.

It is an amenable number.

21787421085 is a deficient number, since it is larger than the sum of its proper divisors (19676450403).

21787421085 is a wasteful number, since it uses less digits than its factorization.

21787421085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4235 (or 4232 counting only the distinct ones).

The product of its (nonzero) digits is 250880, while the sum is 45.

Adding to 21787421085 its reverse (58012478712), we get a palindrome (79799899797).

The spelling of 21787421085 in words is "twenty-one billion, seven hundred eighty-seven million, four hundred twenty-one thousand, eighty-five".