21117051 has 8 divisors (see below), whose sum is σ = 31284560. Its totient is φ = 14078016.

The previous prime is 21117049. The next prime is 21117067. The reversal of 21117051 is 15071112.

It is a happy number.

It is not a de Polignac number, because 21117051 - 2¹ = 21117049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21117001) 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, 391030 + ... + 391083.

It is an arithmetic number, because the mean of its divisors is an integer number (3910570).

Almost surely, 2^21117051 is an apocalyptic number.

21117051 is a deficient number, since it is larger than the sum of its proper divisors (10167509).

21117051 is an equidigital number, since it uses as much as digits as its factorization.

21117051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782122 (or 782116 counting only the distinct ones).

The product of its (nonzero) digits is 70, while the sum is 18.

The square root of 21117051 is about 4595.3292591500. The cubic root of 21117051 is about 276.4040631735.

Adding to 21117051 its reverse (15071112), we get a palindrome (36188163).

The spelling of 21117051 in words is "twenty-one million, one hundred seventeen thousand, fifty-one".