19981237 has 4 divisors (see below), whose sum is σ = 20035180. Its totient is φ = 19927296.

The previous prime is 19981231. The next prime is 19981243. The reversal of 19981237 is 73218991.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (19981231) and next prime (19981243).

It can be written as a sum of positive squares in 2 ways, for example, as 5948721 + 14032516 = 2439^2 + 3746^2 .

It is a 4-Lehmer number, since φ(19981237) divides (19981237-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 19981237 - 2³ = 19981229 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19981237.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19981231) 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 3 ways as a sum of consecutive naturals, for example, 26412 + ... + 27157.

It is an arithmetic number, because the mean of its divisors is an integer number (5008795).

Almost surely, 2^19981237 is an apocalyptic number.

It is an amenable number.

19981237 is a deficient number, since it is larger than the sum of its proper divisors (53943).

19981237 is an equidigital number, since it uses as much as digits as its factorization.

19981237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53942.

The product of its digits is 27216, while the sum is 40.

The square root of 19981237 is about 4470.0376955905. The cubic root of 19981237 is about 271.3568507380.

The spelling of 19981237 in words is "nineteen million, nine hundred eighty-one thousand, two hundred thirty-seven".