21152621 has 8 divisors (see below), whose sum is σ = 24584640. Its totient is φ = 17823168.

The previous prime is 21152591. The next prime is 21152657. The reversal of 21152621 is 12625112.

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 21152621 - 2¹⁴ = 21136237 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21152593 and 21152602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21152321) 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, 25196 + ... + 26021.

It is an arithmetic number, because the mean of its divisors is an integer number (3073080).

Almost surely, 2^21152621 is an apocalyptic number.

It is an amenable number.

21152621 is a deficient number, since it is larger than the sum of its proper divisors (3432019).

21152621 is an equidigital number, since it uses as much as digits as its factorization.

21152621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51283.

The product of its digits is 240, while the sum is 20.

The square root of 21152621 is about 4599.1978648456. The cubic root of 21152621 is about 276.5591697025.

Adding to 21152621 its reverse (12625112), we get a palindrome (33777733).

The spelling of 21152621 in words is "twenty-one million, one hundred fifty-two thousand, six hundred twenty-one".