21251142 has 48 divisors (see below), whose sum is σ = 51976080. Its totient is φ = 6216000.

The previous prime is 21251141. The next prime is 21251179. The reversal of 21251142 is 24115212.

It is a super-2 number, since 2×21251142² = 903222072608328, which contains 22 as substring.

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

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251141) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3892 + ... + 7592.

It is an arithmetic number, because the mean of its divisors is an integer number (1082835).

Almost surely, 2^21251142 is an apocalyptic number.

21251142 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21251142, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25988040).

21251142 is an abundant number, since it is smaller than the sum of its proper divisors (30724938).

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

21251142 is a wasteful number, since it uses less digits than its factorization.

21251142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3749 (or 3746 counting only the distinct ones).

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

The square root of 21251142 is about 4609.8960942737. The cubic root of 21251142 is about 276.9878745447.

Adding to 21251142 its reverse (24115212), we get a palindrome (45366354).

The spelling of 21251142 in words is "twenty-one million, two hundred fifty-one thousand, one hundred forty-two".