21220471 has 8 divisors (see below), whose sum is σ = 22850640. Its totient is φ = 19632768.

The previous prime is 21220429. The next prime is 21220477. The reversal of 21220471 is 17402212.

It is a happy number.

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 21220471 - 2²¹ = 19123319 is a prime.

It is a super-3 number, since 3×21220471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220477) 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, 9576 + ... + 11581.

It is an arithmetic number, because the mean of its divisors is an integer number (2856330).

Almost surely, 2^21220471 is an apocalyptic number.

21220471 is a deficient number, since it is larger than the sum of its proper divisors (1630169).

21220471 is a wasteful number, since it uses less digits than its factorization.

21220471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21233.

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 21220471 is about 4606.5682454513. The cubic root of 21220471 is about 276.8545548787.

Adding to 21220471 its reverse (17402212), we get a palindrome (38622683).

The spelling of 21220471 in words is "twenty-one million, two hundred twenty thousand, four hundred seventy-one".