21425621 has 8 divisors (see below), whose sum is σ = 24948864. Its totient is φ = 18018000.

The previous prime is 21425603. The next prime is 21425639. The reversal of 21425621 is 12652412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21425603) and next prime (21425639).

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

It is a de Polignac number, because none of the positive numbers 2^k-21425621 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 (21425641) 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, 28505 + ... + 29246.

It is an arithmetic number, because the mean of its divisors is an integer number (3118608).

Almost surely, 2^21425621 is an apocalyptic number.

It is an amenable number.

21425621 is a deficient number, since it is larger than the sum of its proper divisors (3523243).

21425621 is an equidigital number, since it uses as much as digits as its factorization.

21425621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57811.

The product of its digits is 960, while the sum is 23.

The square root of 21425621 is about 4628.7818051837. The cubic root of 21425621 is about 277.7438637648.

The spelling of 21425621 in words is "twenty-one million, four hundred twenty-five thousand, six hundred twenty-one".