21020012 has 48 divisors (see below), whose sum is σ = 41912640. Its totient is φ = 9155328.

The previous prime is 21020011. The next prime is 21020017. The reversal of 21020012 is 21002012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020011) 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, 79793 + ... + 80055.

It is an arithmetic number, because the mean of its divisors is an integer number (873180).

Almost surely, 2^21020012 is an apocalyptic number.

It is an amenable number.

21020012 is a deficient number, since it is larger than the sum of its proper divisors (20892628).

21020012 is a wasteful number, since it uses less digits than its factorization.

21020012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362 (or 360 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 21020012 is about 4584.7586632232. The cubic root of 21020012 is about 275.9800272602.

Adding to 21020012 its reverse (21002012), we get a palindrome (42022024).

The spelling of 21020012 in words is "twenty-one million, twenty thousand, twelve".