19981611 has 24 divisors (see below), whose sum is σ = 31558800. Its totient is φ = 12108096.

The previous prime is 19981567. The next prime is 19981649. The reversal of 19981611 is 11618991.

It is not a de Polignac number, because 19981611 - 2²² = 15787307 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19989611) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6565 + ... + 9113.

It is an arithmetic number, because the mean of its divisors is an integer number (1314950).

Almost surely, 2^19981611 is an apocalyptic number.

19981611 is a deficient number, since it is larger than the sum of its proper divisors (11577189).

19981611 is a wasteful number, since it uses less digits than its factorization.

19981611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2635 (or 2632 counting only the distinct ones).

The product of its digits is 3888, while the sum is 36.

The square root of 19981611 is about 4470.0795294939. The cubic root of 19981611 is about 271.3585437735.

It can be divided in two parts, 199 and 81611, that added together give a triangular number (81810 = T₄₀₄).

The spelling of 19981611 in words is "nineteen million, nine hundred eighty-one thousand, six hundred eleven".