21655201 has 2 divisors, whose sum is σ = 21655202. Its totient is φ = 21655200.

The previous prime is 21655189. The next prime is 21655211. The reversal of 21655201 is 10255612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10923025 + 10732176 = 3305^2 + 3276^2 .

It is a cyclic number.

It is not a de Polignac number, because 21655201 - 2¹¹ = 21653153 is a prime.

It is not a weakly prime, because it can be changed into another prime (21655211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10827600 + 10827601.

It is an arithmetic number, because the mean of its divisors is an integer number (10827601).

Almost surely, 2^21655201 is an apocalyptic number.

It is an amenable number.

21655201 is a deficient number, since it is larger than the sum of its proper divisors (1).

21655201 is an equidigital number, since it uses as much as digits as its factorization.

21655201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 21655201 is about 4653.5149081098. The cubic root of 21655201 is about 278.7323692657.

The spelling of 21655201 in words is "twenty-one million, six hundred fifty-five thousand, two hundred one".