87447991 has 2 divisors, whose sum is σ = 87447992. Its totient is φ = 87447990.

The previous prime is 87447989. The next prime is 87448003. The reversal of 87447991 is 19974478.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 87447991 - 2¹ = 87447989 is a prime.

It is a super-2 number, since 2×87447991² = 15294302259872162, which contains 22 as substring.

Together with 87447989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87447911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43723995 + 43723996.

It is an arithmetic number, because the mean of its divisors is an integer number (43723996).

Almost surely, 2^87447991 is an apocalyptic number.

87447991 is a deficient number, since it is larger than the sum of its proper divisors (1).

87447991 is an equidigital number, since it uses as much as digits as its factorization.

87447991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 508032, while the sum is 49.

The square root of 87447991 is about 9351.3630557262. The cubic root of 87447991 is about 443.8640234395.

The spelling of 87447991 in words is "eighty-seven million, four hundred forty-seven thousand, nine hundred ninety-one".