86991021 has 24 divisors (see below), whose sum is σ = 138474336. Its totient is φ = 52284960.

The previous prime is 86991017. The next prime is 86991029. The reversal of 86991021 is 12019968.

It is not a de Polignac number, because 86991021 - 2² = 86991017 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (86991029) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3615 + ... + 13676.

It is an arithmetic number, because the mean of its divisors is an integer number (5769764).

Almost surely, 2^86991021 is an apocalyptic number.

It is an amenable number.

86991021 is a deficient number, since it is larger than the sum of its proper divisors (51483315).

86991021 is a wasteful number, since it uses less digits than its factorization.

86991021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17353 (or 17350 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 86991021 is about 9326.8977157466. The cubic root of 86991021 is about 443.0895178225.

The spelling of 86991021 in words is "eighty-six million, nine hundred ninety-one thousand, twenty-one".