21790471 has 2 divisors, whose sum is σ = 21790472. Its totient is φ = 21790470.

The previous prime is 21790459. The next prime is 21790487. The reversal of 21790471 is 17409712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21790471 - 2¹³ = 21782279 is a prime.

It is a super-3 number, since 3×21790471³ (a number of 23 digits) contains 333 as substring.

It is a plaindrome in base 11.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21790421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10895235 + 10895236.

It is an arithmetic number, because the mean of its divisors is an integer number (10895236).

Almost surely, 2^21790471 is an apocalyptic number.

21790471 is a deficient number, since it is larger than the sum of its proper divisors (1).

21790471 is an equidigital number, since it uses as much as digits as its factorization.

21790471 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3528, while the sum is 31.

The square root of 21790471 is about 4668.0264566517. The cubic root of 21790471 is about 279.3115356311.

The spelling of 21790471 in words is "twenty-one million, seven hundred ninety thousand, four hundred seventy-one".