21402541 has 4 divisors (see below), whose sum is σ = 22661532. Its totient is φ = 20143552.

The previous prime is 21402527. The next prime is 21402587. The reversal of 21402541 is 14520412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9326916 + 12075625 = 3054^2 + 3475^2 .

It is a cyclic number.

It is not a de Polignac number, because 21402541 - 2¹¹ = 21400493 is a prime.

It is a super-2 number, since 2×21402541² = 916137522513362, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21409541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 629470 + ... + 629503.

It is an arithmetic number, because the mean of its divisors is an integer number (5665383).

Almost surely, 2^21402541 is an apocalyptic number.

It is an amenable number.

21402541 is a deficient number, since it is larger than the sum of its proper divisors (1258991).

21402541 is a wasteful number, since it uses less digits than its factorization.

21402541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1258990.

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21402541 is about 4626.2880368607. The cubic root of 21402541 is about 277.6440979825.

Adding to 21402541 its reverse (14520412), we get a palindrome (35922953).

It can be divided in two parts, 2 and 1402541, that multiplied together give a palindrome (2805082).

The spelling of 21402541 in words is "twenty-one million, four hundred two thousand, five hundred forty-one".