1945981 has 2 divisors, whose sum is σ = 1945982. Its totient is φ = 1945980.

The previous prime is 1945969. The next prime is 1945991. The reversal of 1945981 is 1895491.

It is the 570-th star number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1625625 + 320356 = 1275^2 + 566^2 .

It is a cyclic number.

It is not a de Polignac number, because 1945981 - 2¹⁵ = 1913213 is a prime.

It is a super-2 number, since 2×1945981² = 7573684104722, which contains 22 as substring.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 1945981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1945991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 972990 + 972991.

It is an arithmetic number, because the mean of its divisors is an integer number (972991).

2^1945981 is an apocalyptic number.

It is an amenable number.

1945981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1945981 is an equidigital number, since it uses as much as digits as its factorization.

1945981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 37.

The square root of 1945981 is about 1394.9842293015. The cubic root of 1945981 is about 124.8474084691.

It can be divided in two parts, 1945 and 981, that added together give a triangular number (2926 = T₇₆).

The spelling of 1945981 in words is "one million, nine hundred forty-five thousand, nine hundred eighty-one".