21522621 has 8 divisors (see below), whose sum is σ = 28903840. Its totient is φ = 14244912.

The previous prime is 21522619. The next prime is 21522671. The reversal of 21522621 is 12622512.

It is a happy number.

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

It is not a de Polignac number, because 21522621 - 2¹ = 21522619 is a prime.

It is a super-3 number, since 3×21522621³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21522601) 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, 25390 + ... + 26223.

It is an arithmetic number, because the mean of its divisors is an integer number (3612980).

Almost surely, 2^21522621 is an apocalyptic number.

It is an amenable number.

21522621 is a deficient number, since it is larger than the sum of its proper divisors (7381219).

21522621 is a wasteful number, since it uses less digits than its factorization.

21522621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51755.

The product of its digits is 480, while the sum is 21.

The square root of 21522621 is about 4639.2478916307. The cubic root of 21522621 is about 278.1623751649.

The spelling of 21522621 in words is "twenty-one million, five hundred twenty-two thousand, six hundred twenty-one".