21000010985 has 8 divisors (see below), whose sum is σ = 25298069256. Its totient is φ = 16734638080.

The previous prime is 21000010973. The next prime is 21000010991. The reversal of 21000010985 is 58901000012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14920378201 + 6079632784 = 122149^2 + 77972^2 .

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

It is not a de Polignac number, because 21000010985 - 2³⁰ = 19926269161 is a prime.

It is a super-2 number, since 2×21000010985² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8169926 + ... + 8172495.

It is an arithmetic number, because the mean of its divisors is an integer number (3162258657).

Almost surely, 2^21000010985 is an apocalyptic number.

It is an amenable number.

21000010985 is a deficient number, since it is larger than the sum of its proper divisors (4298058271).

21000010985 is a wasteful number, since it uses less digits than its factorization.

21000010985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16342683.

The product of its (nonzero) digits is 720, while the sum is 26.

Adding to 21000010985 its reverse (58901000012), we get a palindrome (79901010997).

The spelling of 21000010985 in words is "twenty-one billion, ten thousand, nine hundred eighty-five".