2197781 has 2 divisors, whose sum is σ = 2197782. Its totient is φ = 2197780.

The previous prime is 2197771. The next prime is 2197799. The reversal of 2197781 is 1877912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2044900 + 152881 = 1430^2 + 391^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2197781 is a prime.

It is a super-2 number, since 2×2197781² = 9660482647922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2197771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1098890 + 1098891.

It is an arithmetic number, because the mean of its divisors is an integer number (1098891).

2^2197781 is an apocalyptic number.

It is an amenable number.

2197781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2197781 is an equidigital number, since it uses as much as digits as its factorization.

2197781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7056, while the sum is 35.

The square root of 2197781 is about 1482.4914839553. The cubic root of 2197781 is about 130.0154025143.

It can be divided in two parts, 219 and 7781, that added together give a cube (8000 = 20³).

The spelling of 2197781 in words is "two million, one hundred ninety-seven thousand, seven hundred eighty-one".