91021001 has 4 divisors (see below), whose sum is σ = 95811600. Its totient is φ = 86230404.

The previous prime is 91020989. The next prime is 91021013. The reversal of 91021001 is 10012019.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (91020989) and next prime (91021013).

It is a cyclic number.

It is not a de Polignac number, because 91021001 - 2²² = 86826697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91021031) 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, 2395271 + ... + 2395308.

It is an arithmetic number, because the mean of its divisors is an integer number (23952900).

Almost surely, 2^91021001 is an apocalyptic number.

It is an amenable number.

91021001 is a deficient number, since it is larger than the sum of its proper divisors (4790599).

91021001 is a wasteful number, since it uses less digits than its factorization.

91021001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4790598.

The product of its (nonzero) digits is 18, while the sum is 14.

The square root of 91021001 is about 9540.4927021617. The cubic root of 91021001 is about 449.8287430633.

The spelling of 91021001 in words is "ninety-one million, twenty-one thousand, one".