21080685 has 16 divisors (see below), whose sum is σ = 34283520. Its totient is φ = 11058240.

The previous prime is 21080677. The next prime is 21080687. The reversal of 21080685 is 58608012.

It is not a de Polignac number, because 21080685 - 2³ = 21080677 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21080687) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10605 + ... + 12434.

It is an arithmetic number, because the mean of its divisors is an integer number (2142720).

Almost surely, 2^21080685 is an apocalyptic number.

It is an amenable number.

21080685 is a deficient number, since it is larger than the sum of its proper divisors (13202835).

21080685 is a wasteful number, since it uses less digits than its factorization.

21080685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23108.

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 21080685 is about 4591.3707103653. The cubic root of 21080685 is about 276.2453054354.

Adding to 21080685 its reverse (58608012), we get a palindrome (79688697).

The spelling of 21080685 in words is "twenty-one million, eighty thousand, six hundred eighty-five".