21253144 has 16 divisors (see below), whose sum is σ = 43472520. Its totient is φ = 9660480.

The previous prime is 21253121. The next prime is 21253181. The reversal of 21253144 is 44135212.

It is a super-2 number, since 2×21253144² = 903392259769472, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120669 + ... + 120844.

Almost surely, 2^21253144 is an apocalyptic number.

It is an amenable number.

21253144 is an abundant number, since it is smaller than the sum of its proper divisors (22219376).

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

21253144 is a wasteful number, since it uses less digits than its factorization.

21253144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241530 (or 241526 counting only the distinct ones).

The product of its digits is 960, while the sum is 22.

The square root of 21253144 is about 4610.1132307135. The cubic root of 21253144 is about 276.9965723096.

Adding to 21253144 its reverse (44135212), we get a palindrome (65388356).

It can be divided in two parts, 212531 and 44, that multiplied together give a square (9351364 = 3058²).

The spelling of 21253144 in words is "twenty-one million, two hundred fifty-three thousand, one hundred forty-four".