20837221 has 2 divisors, whose sum is σ = 20837222. Its totient is φ = 20837220.

The previous prime is 20837213. The next prime is 20837231. The reversal of 20837221 is 12273802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19236996 + 1600225 = 4386^2 + 1265^2 .

It is a cyclic number.

It is not a de Polignac number, because 20837221 - 2³ = 20837213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20837231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10418610 + 10418611.

It is an arithmetic number, because the mean of its divisors is an integer number (10418611).

Almost surely, 2^20837221 is an apocalyptic number.

It is an amenable number.

20837221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20837221 is an equidigital number, since it uses as much as digits as its factorization.

20837221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 20837221 is about 4564.7804985563. The cubic root of 20837221 is about 275.1777187334.

The spelling of 20837221 in words is "twenty million, eight hundred thirty-seven thousand, two hundred twenty-one".