21047621 has 8 divisors (see below), whose sum is σ = 24099264. Its totient is φ = 18007200.

The previous prime is 21047617. The next prime is 21047629. The reversal of 21047621 is 12674012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21047621 - 2² = 21047617 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21047629) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1706 + ... + 6708.

It is an arithmetic number, because the mean of its divisors is an integer number (3012408).

Almost surely, 2^21047621 is an apocalyptic number.

It is an amenable number.

21047621 is a deficient number, since it is larger than the sum of its proper divisors (3051643).

21047621 is an equidigital number, since it uses as much as digits as its factorization.

21047621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5611.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21047621 is about 4587.7686297371. The cubic root of 21047621 is about 276.1008042133.

The spelling of 21047621 in words is "twenty-one million, forty-seven thousand, six hundred twenty-one".