21056461 has 4 divisors (see below), whose sum is σ = 21093532. Its totient is φ = 21019392.

The previous prime is 21056459. The next prime is 21056479. The reversal of 21056461 is 16465012.

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 11600836 + 9455625 = 3406^2 + 3075^2 .

It is a cyclic number.

It is not a de Polignac number, because 21056461 - 2¹ = 21056459 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 (21056401) 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, 17670 + ... + 18823.

It is an arithmetic number, because the mean of its divisors is an integer number (5273383).

Almost surely, 2^21056461 is an apocalyptic number.

It is an amenable number.

21056461 is a deficient number, since it is larger than the sum of its proper divisors (37071).

21056461 is an equidigital number, since it uses as much as digits as its factorization.

21056461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37070.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21056461 is about 4588.7319599210. The cubic root of 21056461 is about 276.1394529120.

The spelling of 21056461 in words is "twenty-one million, fifty-six thousand, four hundred sixty-one".