21140921 has 2 divisors, whose sum is σ = 21140922. Its totient is φ = 21140920.

The previous prime is 21140909. The next prime is 21140957. The reversal of 21140921 is 12904112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21114025 + 26896 = 4595^2 + 164^2 .

It is a cyclic number.

It is not a de Polignac number, because 21140921 - 2⁶ = 21140857 is a prime.

It is a Chen prime.

It is equal to p_1338320 and since 21140921 and 1338320 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 21140893 and 21140902.

It is not a weakly prime, because it can be changed into another prime (21140621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10570460 + 10570461.

It is an arithmetic number, because the mean of its divisors is an integer number (10570461).

Almost surely, 2^21140921 is an apocalyptic number.

It is an amenable number.

21140921 is a deficient number, since it is larger than the sum of its proper divisors (1).

21140921 is an equidigital number, since it uses as much as digits as its factorization.

21140921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 21140921 is about 4597.9257279778. The cubic root of 21140921 is about 276.5081698909.

The spelling of 21140921 in words is "twenty-one million, one hundred forty thousand, nine hundred twenty-one".