20928251 has 2 divisors, whose sum is σ = 20928252. Its totient is φ = 20928250.

The previous prime is 20928247. The next prime is 20928283. The reversal of 20928251 is 15282902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20928251 - 2² = 20928247 is a prime.

It is not a weakly prime, because it can be changed into another prime (20928851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10464125 + 10464126.

It is an arithmetic number, because the mean of its divisors is an integer number (10464126).

Almost surely, 2^20928251 is an apocalyptic number.

20928251 is a deficient number, since it is larger than the sum of its proper divisors (1).

20928251 is an equidigital number, since it uses as much as digits as its factorization.

20928251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 20928251 is about 4574.7405390907. The cubic root of 20928251 is about 275.5778526864.

The spelling of 20928251 in words is "twenty million, nine hundred twenty-eight thousand, two hundred fifty-one".