21532061 has 4 divisors (see below), whose sum is σ = 21543324. Its totient is φ = 21520800.

The previous prime is 21532051. The next prime is 21532067. The reversal of 21532061 is 16023512.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 7236100 + 14295961 = 2690^2 + 3781^2 .

It is a cyclic number.

It is not a de Polignac number, because 21532061 - 2¹⁴ = 21515677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21532067) 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, 1970 + ... + 6851.

It is an arithmetic number, because the mean of its divisors is an integer number (5385831).

Almost surely, 2^21532061 is an apocalyptic number.

It is an amenable number.

21532061 is a deficient number, since it is larger than the sum of its proper divisors (11263).

21532061 is an equidigital number, since it uses as much as digits as its factorization.

21532061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11262.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21532061 is about 4640.2651863875. The cubic root of 21532061 is about 278.2030373285.

Adding to 21532061 its reverse (16023512), we get a palindrome (37555573).

The spelling of 21532061 in words is "twenty-one million, five hundred thirty-two thousand, sixty-one".