21601212 has 24 divisors (see below), whose sum is σ = 50480976. Its totient is φ = 7189248.

The previous prime is 21601189. The next prime is 21601277. The reversal of 21601212 is 21210612.

It is a super-2 number, since 2×21601212² = 933224719737888, which contains 22 as substring.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21601191 and 21601200.

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, 11268 + ... + 13044.

It is an arithmetic number, because the mean of its divisors is an integer number (2103374).

Almost surely, 2^21601212 is an apocalyptic number.

It is an amenable number.

21601212 is an abundant number, since it is smaller than the sum of its proper divisors (28879764).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21601212 is a wasteful number, since it uses less digits than its factorization.

21601212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2797 (or 2795 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 21601212 is about 4647.7104040592. The cubic root of 21601212 is about 278.5005388135.

Adding to 21601212 its reverse (21210612), we get a palindrome (42811824).

The spelling of 21601212 in words is "twenty-one million, six hundred one thousand, two hundred twelve".