21012085 has 8 divisors (see below), whose sum is σ = 26697816. Its totient is φ = 15820800.

The previous prime is 21012077. The next prime is 21012091. The reversal of 21012085 is 58021012.

It can be written as a sum of positive squares in 4 ways, for example, as 4835601 + 16176484 = 2199^2 + 4022^2 .

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

It is not a de Polignac number, because 21012085 - 2³ = 21012077 is a prime.

It is a Duffinian number.

It is a congruent 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, 123516 + ... + 123685.

It is an arithmetic number, because the mean of its divisors is an integer number (3337227).

Almost surely, 2^21012085 is an apocalyptic number.

It is an amenable number.

21012085 is a deficient number, since it is larger than the sum of its proper divisors (5685731).

21012085 is a wasteful number, since it uses less digits than its factorization.

21012085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247223.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 21012085 is about 4583.8940869091. The cubic root of 21012085 is about 275.9453306618.

Adding to 21012085 its reverse (58021012), we get a palindrome (79033097).

It can be divided in two parts, 2101 and 2085, that added together give a triangular number (4186 = T₉₁).

The spelling of 21012085 in words is "twenty-one million, twelve thousand, eighty-five".