21121071 has 16 divisors (see below), whose sum is σ = 28680288. Its totient is φ = 13824000.

The previous prime is 21121069. The next prime is 21121081. The reversal of 21121071 is 17012112.

It is not a de Polignac number, because 21121071 - 2¹ = 21121069 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21121071.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52471 + ... + 52871.

It is an arithmetic number, because the mean of its divisors is an integer number (1792518).

Almost surely, 2^21121071 is an apocalyptic number.

21121071 is a deficient number, since it is larger than the sum of its proper divisors (7559217).

21121071 is a wasteful number, since it uses less digits than its factorization.

21121071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 682.

The product of its (nonzero) digits is 28, while the sum is 15.

The square root of 21121071 is about 4595.7666389842. The cubic root of 21121071 is about 276.4216015099.

Adding to 21121071 its reverse (17012112), we get a palindrome (38133183).

The spelling of 21121071 in words is "twenty-one million, one hundred twenty-one thousand, seventy-one".