1987281621 has 40 divisors (see below), whose sum is σ = 3215787960. Its totient is φ = 1215762048.

The previous prime is 1987281617. The next prime is 1987281631. The reversal of 1987281621 is 1261827891.

1987281621 is a `hidden beast` number, since 19 + 8 + 7 + 2 + 8 + 1 + 621 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 171243396 + 1816038225 = 13086^2 + 42615^2 .

It is not a de Polignac number, because 1987281621 - 2² = 1987281617 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987281631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 176715 + ... + 187623.

It is an arithmetic number, because the mean of its divisors is an integer number (80394699).

Almost surely, 2^1987281621 is an apocalyptic number.

It is an amenable number.

1987281621 is a deficient number, since it is larger than the sum of its proper divisors (1228506339).

1987281621 is a wasteful number, since it uses less digits than its factorization.

1987281621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11107 (or 11098 counting only the distinct ones).

The product of its digits is 96768, while the sum is 45.

The square root of 1987281621 is about 44578.9369657914. The cubic root of 1987281621 is about 1257.2446764264.

The spelling of 1987281621 in words is "one billion, nine hundred eighty-seven million, two hundred eighty-one thousand, six hundred twenty-one".