1987631 has 4 divisors (see below), whose sum is σ = 2056200. Its totient is φ = 1919064.

The previous prime is 1987621. The next prime is 1987649. The reversal of 1987631 is 1367891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1367891 = 7 ⋅195413.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1987631 is a prime.

It is a super-2 number, since 2×1987631² = 7901353984322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1987591 and 1987600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987621) 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, 34241 + ... + 34298.

It is an arithmetic number, because the mean of its divisors is an integer number (514050).

2^1987631 is an apocalyptic number.

1987631 is a deficient number, since it is larger than the sum of its proper divisors (68569).

1987631 is an equidigital number, since it uses as much as digits as its factorization.

1987631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68568.

The product of its digits is 9072, while the sum is 35.

The square root of 1987631 is about 1409.8336781337. The cubic root of 1987631 is about 125.7318349787.

The spelling of 1987631 in words is "one million, nine hundred eighty-seven thousand, six hundred thirty-one".