16642981 has 2 divisors, whose sum is σ = 16642982. Its totient is φ = 16642980.

The previous prime is 16642973. The next prime is 16643023. The reversal of 16642981 is 18924661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11329956 + 5313025 = 3366^2 + 2305^2 .

It is a cyclic number.

It is not a de Polignac number, because 16642981 - 2³ = 16642973 is a prime.

It is a super-2 number, since 2×16642981² = 553977633132722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16642981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16642931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8321490 + 8321491.

It is an arithmetic number, because the mean of its divisors is an integer number (8321491).

Almost surely, 2^16642981 is an apocalyptic number.

It is an amenable number.

16642981 is a deficient number, since it is larger than the sum of its proper divisors (1).

16642981 is an equidigital number, since it uses as much as digits as its factorization.

16642981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 37.

The square root of 16642981 is about 4079.5809833854. The cubic root of 16642981 is about 255.3154164330.

The spelling of 16642981 in words is "sixteen million, six hundred forty-two thousand, nine hundred eighty-one".