19906987 has 4 divisors (see below), whose sum is σ = 19996480. Its totient is φ = 19817496.

The previous prime is 19906981. The next prime is 19906993. The reversal of 19906987 is 78960991.

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 (19906981) and next prime (19906993).

It is a cyclic number.

It is not a de Polignac number, because 19906987 - 2¹⁵ = 19874219 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 19906987.

It is not an unprimeable number, because it can be changed into a prime (19906981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44412 + ... + 44857.

It is an arithmetic number, because the mean of its divisors is an integer number (4999120).

Almost surely, 2^19906987 is an apocalyptic number.

19906987 is a deficient number, since it is larger than the sum of its proper divisors (89493).

19906987 is an equidigital number, since it uses as much as digits as its factorization.

19906987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89492.

The product of its (nonzero) digits is 244944, while the sum is 49.

The square root of 19906987 is about 4461.7246665387. The cubic root of 19906987 is about 271.0203141047.

The spelling of 19906987 in words is "nineteen million, nine hundred six thousand, nine hundred eighty-seven".