21011172 has 96 divisors (see below), whose sum is σ = 61415424. Its totient is φ = 5443200.

The previous prime is 21011143. The next prime is 21011173. The reversal of 21011172 is 27111012.

It is not an unprimeable number, because it can be changed into a prime (21011173) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 77397 + ... + 77667.

It is an arithmetic number, because the mean of its divisors is an integer number (639744).

Almost surely, 2^21011172 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 21011172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30707712).

21011172 is an abundant number, since it is smaller than the sum of its proper divisors (40404252).

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

21011172 is a wasteful number, since it uses less digits than its factorization.

21011172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369 (or 367 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 15.

The square root of 21011172 is about 4583.7944980114. The cubic root of 21011172 is about 275.9413338867.

Adding to 21011172 its reverse (27111012), we get a palindrome (48122184).

The spelling of 21011172 in words is "twenty-one million, eleven thousand, one hundred seventy-two".