21351072 has 48 divisors (see below), whose sum is σ = 57570912. Its totient is φ = 6923520.

The previous prime is 21351053. The next prime is 21351073. The reversal of 21351072 is 27015312.

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (21351073) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 547 + ... + 6557.

It is an arithmetic number, because the mean of its divisors is an integer number (1199394).

Almost surely, 2^21351072 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 21351072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28785456).

21351072 is an abundant number, since it is smaller than the sum of its proper divisors (36219840).

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

21351072 is a wasteful number, since it uses less digits than its factorization.

21351072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6061 (or 6053 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21351072 is about 4620.7220215027. The cubic root of 21351072 is about 277.4213590974.

Adding to 21351072 its reverse (27015312), we get a palindrome (48366384).

The spelling of 21351072 in words is "twenty-one million, three hundred fifty-one thousand, seventy-two".