20540921 has 2 divisors, whose sum is σ = 20540922. Its totient is φ = 20540920.

The previous prime is 20540917. The next prime is 20540951. The reversal of 20540921 is 12904502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10530025 + 10010896 = 3245^2 + 3164^2 .

It is a cyclic number.

It is not a de Polignac number, because 20540921 - 2² = 20540917 is a prime.

It is not a weakly prime, because it can be changed into another prime (20540951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10270460 + 10270461.

It is an arithmetic number, because the mean of its divisors is an integer number (10270461).

Almost surely, 2^20540921 is an apocalyptic number.

It is an amenable number.

20540921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20540921 is an equidigital number, since it uses as much as digits as its factorization.

20540921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 20540921 is about 4532.2092846646. The cubic root of 20540921 is about 273.8671679306.

The spelling of 20540921 in words is "twenty million, five hundred forty thousand, nine hundred twenty-one".