21290071 has 12 divisors (see below), whose sum is σ = 23528232. Its totient is φ = 19250000.

The previous prime is 21290039. The next prime is 21290083. The reversal of 21290071 is 17009212.

It is not a de Polignac number, because 21290071 - 2⁵ = 21290039 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 (21290021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30021 + ... + 30721.

It is an arithmetic number, because the mean of its divisors is an integer number (1960686).

Almost surely, 2^21290071 is an apocalyptic number.

21290071 is a deficient number, since it is larger than the sum of its proper divisors (2238161).

21290071 is a wasteful number, since it uses less digits than its factorization.

21290071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 974 (or 963 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 21290071 is about 4614.1164918108. The cubic root of 21290071 is about 277.1569052012.

Adding to 21290071 its reverse (17009212), we get a palindrome (38299283).

It can be divided in two parts, 21 and 290071, that added together give a palindrome (290092).

The spelling of 21290071 in words is "twenty-one million, two hundred ninety thousand, seventy-one".