21142281 has 8 divisors (see below), whose sum is σ = 28951744. Its totient is φ = 13713840.

The previous prime is 21142273. The next prime is 21142291. The reversal of 21142281 is 18224112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21142281 - 2³ = 21142273 is a prime.

It is a super-2 number, since 2×21142281² = 893992091765922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21142201) 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, 95125 + ... + 95346.

It is an arithmetic number, because the mean of its divisors is an integer number (3618968).

Almost surely, 2^21142281 is an apocalyptic number.

It is an amenable number.

21142281 is a deficient number, since it is larger than the sum of its proper divisors (7809463).

21142281 is a wasteful number, since it uses less digits than its factorization.

21142281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190511.

The product of its digits is 256, while the sum is 21.

The square root of 21142281 is about 4598.0736183754. The cubic root of 21142281 is about 276.5140990405.

Adding to 21142281 its reverse (18224112), we get a palindrome (39366393).

The spelling of 21142281 in words is "twenty-one million, one hundred forty-two thousand, two hundred eighty-one".