21421512 has 96 divisors (see below), whose sum is σ = 69825600. Its totient is φ = 5795712.

The previous prime is 21421489. The next prime is 21421537. The reversal of 21421512 is 21512412.

It is a super-2 number, since 2×21421512² = 917762352732288, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8458 + ... + 10694.

It is an arithmetic number, because the mean of its divisors is an integer number (727350).

Almost surely, 2^21421512 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21421512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34912800).

21421512 is an abundant number, since it is smaller than the sum of its proper divisors (48404088).

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

21421512 is a wasteful number, since it uses less digits than its factorization.

21421512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2275 (or 2268 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 21421512 is about 4628.3379306183. The cubic root of 21421512 is about 277.7261074144.

Adding to 21421512 its reverse (21512412), we get a palindrome (42933924).

The spelling of 21421512 in words is "twenty-one million, four hundred twenty-one thousand, five hundred twelve".