21520012 has 6 divisors (see below), whose sum is σ = 37660028. Its totient is φ = 10760004.

The previous prime is 21520003. The next prime is 21520013. The reversal of 21520012 is 21002512.

It is a super-2 number, since 2×21520012² = 926221832960288, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21519974 and 21520001.

It is not an unprimeable number, because it can be changed into a prime (21520013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2689998 + ... + 2690005.

Almost surely, 2^21520012 is an apocalyptic number.

It is an amenable number.

21520012 is a deficient number, since it is larger than the sum of its proper divisors (16140016).

21520012 is a wasteful number, since it uses less digits than its factorization.

21520012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5380007 (or 5380005 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21520012 is about 4638.9666952889. The cubic root of 21520012 is about 278.1511349762.

Adding to 21520012 its reverse (21002512), we get a palindrome (42522524).

The spelling of 21520012 in words is "twenty-one million, five hundred twenty thousand, twelve".