21534641 has 4 divisors (see below), whose sum is σ = 21547812. Its totient is φ = 21521472.

The previous prime is 21534577. The next prime is 21534659. The reversal of 21534641 is 14643512.

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 18524416 + 3010225 = 4304^2 + 1735^2 .

It is a cyclic number.

It is not a de Polignac number, because 21534641 - 2⁶ = 21534577 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21534641.

It is not an unprimeable number, because it can be changed into a prime (21534041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3716 + ... + 7541.

It is an arithmetic number, because the mean of its divisors is an integer number (5386953).

Almost surely, 2^21534641 is an apocalyptic number.

It is an amenable number.

21534641 is a deficient number, since it is larger than the sum of its proper divisors (13171).

21534641 is a wasteful number, since it uses less digits than its factorization.

21534641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13170.

The product of its digits is 2880, while the sum is 26.

The square root of 21534641 is about 4640.5431794134. The cubic root of 21534641 is about 278.2141484366.

The spelling of 21534641 in words is "twenty-one million, five hundred thirty-four thousand, six hundred forty-one".