16219981 has 2 divisors, whose sum is σ = 16219982. Its totient is φ = 16219980.

The previous prime is 16219933. The next prime is 16220069. The reversal of 16219981 is 18991261.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13213225 + 3006756 = 3635^2 + 1734^2 .

It is a cyclic number.

It is not a de Polignac number, because 16219981 - 2¹¹ = 16217933 is a prime.

It is a super-2 number, since 2×16219981² = 526175567280722, 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 16219981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16219081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8109990 + 8109991.

It is an arithmetic number, because the mean of its divisors is an integer number (8109991).

Almost surely, 2^16219981 is an apocalyptic number.

It is an amenable number.

16219981 is a deficient number, since it is larger than the sum of its proper divisors (1).

16219981 is an equidigital number, since it uses as much as digits as its factorization.

16219981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 37.

The square root of 16219981 is about 4027.4037542814. The cubic root of 16219981 is about 253.1337854188.

The spelling of 16219981 in words is "sixteen million, two hundred nineteen thousand, nine hundred eighty-one".