2156761 has 2 divisors, whose sum is σ = 2156762. Its totient is φ = 2156760.

The previous prime is 2156753. The next prime is 2156789. The reversal of 2156761 is 1676512.

It is an a-pointer prime, because the next prime (2156789) can be obtained adding 2156761 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1265625 + 891136 = 1125^2 + 944^2 .

It is a cyclic number.

It is not a de Polignac number, because 2156761 - 2³ = 2156753 is a prime.

It is a super-2 number, since 2×2156761² = 9303236022242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2156711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1078380 + 1078381.

It is an arithmetic number, because the mean of its divisors is an integer number (1078381).

2^2156761 is an apocalyptic number.

It is an amenable number.

2156761 is a deficient number, since it is larger than the sum of its proper divisors (1).

2156761 is an equidigital number, since it uses as much as digits as its factorization.

2156761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 28.

The square root of 2156761 is about 1468.5915020863. The cubic root of 2156761 is about 129.2014359862.

Subtracting from 2156761 its reverse (1676512), we obtain a square (480249 = 693²).

The spelling of 2156761 in words is "two million, one hundred fifty-six thousand, seven hundred sixty-one".