21542641 has 4 divisors (see below), whose sum is σ = 21557232. Its totient is φ = 21528052.

The previous prime is 21542639. The next prime is 21542663. The reversal of 21542641 is 14624512.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21542641 - 2¹ = 21542639 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21542681) 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, 4795 + ... + 8128.

It is an arithmetic number, because the mean of its divisors is an integer number (5389308).

Almost surely, 2^21542641 is an apocalyptic number.

It is an amenable number.

21542641 is a deficient number, since it is larger than the sum of its proper divisors (14591).

21542641 is a wasteful number, since it uses less digits than its factorization.

21542641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14590.

The product of its digits is 1920, while the sum is 25.

The square root of 21542641 is about 4641.4050674338. The cubic root of 21542641 is about 278.2485958436.

The spelling of 21542641 in words is "twenty-one million, five hundred forty-two thousand, six hundred forty-one".