1987391967 has 16 divisors (see below), whose sum is σ = 2914648320. Its totient is φ = 1204477560.

The previous prime is 1987391957. The next prime is 1987391993. The reversal of 1987391967 is 7691937891.

It is not a de Polignac number, because 1987391967 - 2⁴ = 1987391951 is a prime.

It is a super-2 number, since 2×1987391967² = 7899453660992258178, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1987391967.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987391947) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 244867 + ... + 252852.

It is an arithmetic number, because the mean of its divisors is an integer number (182165520).

Almost surely, 2^1987391967 is an apocalyptic number.

1987391967 is a deficient number, since it is larger than the sum of its proper divisors (927256353).

1987391967 is an equidigital number, since it uses as much as digits as its factorization.

1987391967 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497755 (or 497733 counting only the distinct ones).

The product of its digits is 5143824, while the sum is 60.

The square root of 1987391967 is about 44580.1745958896. The cubic root of 1987391967 is about 1257.2679459607.

The spelling of 1987391967 in words is "one billion, nine hundred eighty-seven million, three hundred ninety-one thousand, nine hundred sixty-seven".