21321061 has 4 divisors (see below), whose sum is σ = 22056300. Its totient is φ = 20585824.

The previous prime is 21321031. The next prime is 21321067. The reversal of 21321061 is 16012312.

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 9036036 + 12285025 = 3006^2 + 3505^2 .

It is not a de Polignac number, because 21321061 - 2²³ = 12932453 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 (21321067) 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, 367576 + ... + 367633.

It is an arithmetic number, because the mean of its divisors is an integer number (5514075).

Almost surely, 2^21321061 is an apocalyptic number.

It is an amenable number.

21321061 is a deficient number, since it is larger than the sum of its proper divisors (735239).

21321061 is an equidigital number, since it uses as much as digits as its factorization.

21321061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 735238.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21321061 is about 4617.4734433454. The cubic root of 21321061 is about 277.2913172848.

Adding to 21321061 its reverse (16012312), we get a palindrome (37333373).

The spelling of 21321061 in words is "twenty-one million, three hundred twenty-one thousand, sixty-one".