21620471 has 2 divisors, whose sum is σ = 21620472. Its totient is φ = 21620470.

The previous prime is 21620453. The next prime is 21620479. The reversal of 21620471 is 17402612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21620471 - 2¹⁰ = 21619447 is a prime.

It is a super-3 number, since 3×21620471³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21620479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810235 + 10810236.

It is an arithmetic number, because the mean of its divisors is an integer number (10810236).

Almost surely, 2^21620471 is an apocalyptic number.

21620471 is a deficient number, since it is larger than the sum of its proper divisors (1).

21620471 is an equidigital number, since it uses as much as digits as its factorization.

21620471 is an evil number, because the sum of its binary digits is even.

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

The square root of 21620471 is about 4649.7818228386. The cubic root of 21620471 is about 278.5832818349.

The spelling of 21620471 in words is "twenty-one million, six hundred twenty thousand, four hundred seventy-one".