221708749 has 2 divisors, whose sum is σ = 221708750. Its totient is φ = 221708748.

The previous prime is 221708743. The next prime is 221708783. The reversal of 221708749 is 947807122.

221708749 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 166874724 + 54834025 = 12918^2 + 7405^2 .

It is a cyclic number.

It is not a de Polignac number, because 221708749 - 2¹⁵ = 221675981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221708743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110854374 + 110854375.

It is an arithmetic number, because the mean of its divisors is an integer number (110854375).

Almost surely, 2^221708749 is an apocalyptic number.

It is an amenable number.

221708749 is a deficient number, since it is larger than the sum of its proper divisors (1).

221708749 is an equidigital number, since it uses as much as digits as its factorization.

221708749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 56448, while the sum is 40.

The square root of 221708749 is about 14889.8874743901. The cubic root of 221708749 is about 605.2399831131.

The spelling of 221708749 in words is "two hundred twenty-one million, seven hundred eight thousand, seven hundred forty-nine".