1629981 has 12 divisors (see below), whose sum is σ = 2393820.
Its totient is φ = 1068480.
The previous prime is 1629937. The next prime is 1629983. The reversal of 1629981 is 1899261.
It can be written as a sum of positive squares in 2 ways, for example, as 27225 + 1602756 = 165^2 + 1266^2
It is not a de Polignac number, because 1629981 - 27 = 1629853 is a prime.
It is a super-2 number, since 2×16299812 = 5313676120722, which contains 22 as substring.
It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.
1629981 is a lucky number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (1629983) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (13) of ones.
It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 936 + ... + 2033.
It is an arithmetic number, because the mean of its divisors is an integer number (199485).
21629981 is an apocalyptic number.
It is an amenable number.
1629981 is a deficient number, since it is larger than the sum of its proper divisors (763839).
1629981 is a wasteful number, since it uses less digits than its factorization.
1629981 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 3036 (or 3033 counting only the distinct ones).
The product of its digits is 7776, while the sum is 36.
The square root of 1629981 is about 1276.7070924844.
The cubic root of 1629981 is about 117.6867349169.
The spelling of 1629981 in words is "one million, six hundred twenty-nine thousand, nine hundred eighty-one".