21420241 has 8 divisors (see below), whose sum is σ = 22213800. Its totient is φ = 20630400.

The previous prime is 21420233. The next prime is 21420251. The reversal of 21420241 is 14202412.

It can be written as a sum of positive squares in 4 ways, for example, as 13719616 + 7700625 = 3704^2 + 2775^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21420241 - 2³ = 21420233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21420251) 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, 16815 + ... + 18043.

It is an arithmetic number, because the mean of its divisors is an integer number (2776725).

Almost surely, 2^21420241 is an apocalyptic number.

It is an amenable number.

21420241 is a deficient number, since it is larger than the sum of its proper divisors (793559).

21420241 is a wasteful number, since it uses less digits than its factorization.

21420241 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1859.

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21420241 is about 4628.2006222721. The cubic root of 21420241 is about 277.7206145425.

Adding to 21420241 its reverse (14202412), we get a palindrome (35622653).

It can be divided in two parts, 2 and 1420241, that multiplied together give a palindrome (2840482).

The spelling of 21420241 in words is "twenty-one million, four hundred twenty thousand, two hundred forty-one".