21121670 has 16 divisors (see below), whose sum is σ = 38126160. Its totient is φ = 8424864.

The previous prime is 21121663. The next prime is 21121679. The reversal of 21121670 is 7612112.

It is a super-2 number, since 2×21121670² = 892249887177800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121679) 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, 1004 + ... + 6576.

It is an arithmetic number, because the mean of its divisors is an integer number (2382885).

Almost surely, 2^21121670 is an apocalyptic number.

21121670 is a deficient number, since it is larger than the sum of its proper divisors (17004490).

21121670 is a wasteful number, since it uses less digits than its factorization.

21121670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5959.

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 21121670 is about 4595.8318071923. The cubic root of 21121670 is about 276.4242146188.

Adding to 21121670 its reverse (7612112), we get a palindrome (28733782).

The spelling of 21121670 in words is "twenty-one million, one hundred twenty-one thousand, six hundred seventy".