21032261 has 4 divisors (see below), whose sum is σ = 21388800. Its totient is φ = 20675724.

The previous prime is 21032237. The next prime is 21032267. The reversal of 21032261 is 16223012.

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 not a de Polignac number, because 21032261 - 2⁶ = 21032197 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 (21032267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 178181 + ... + 178298.

It is an arithmetic number, because the mean of its divisors is an integer number (5347200).

Almost surely, 2^21032261 is an apocalyptic number.

It is an amenable number.

21032261 is a deficient number, since it is larger than the sum of its proper divisors (356539).

21032261 is an equidigital number, since it uses as much as digits as its factorization.

21032261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356538.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21032261 is about 4586.0943077961. The cubic root of 21032261 is about 276.0336241679.

Adding to 21032261 its reverse (16223012), we get a palindrome (37255273).

Subtracting from 21032261 its reverse (16223012), we obtain a square (4809249 = 2193²).

The spelling of 21032261 in words is "twenty-one million, thirty-two thousand, two hundred sixty-one".