91000551 has 4 divisors (see below), whose sum is σ = 121334072. Its totient is φ = 60667032.

The previous prime is 91000549. The next prime is 91000573. The reversal of 91000551 is 15500019.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15500019 = 3 ⋅5166673.

It is not a de Polignac number, because 91000551 - 2¹ = 91000549 is a prime.

It is a super-2 number, since 2×91000551² = 16562200564607202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91000051) 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, 15166756 + ... + 15166761.

It is an arithmetic number, because the mean of its divisors is an integer number (30333518).

Almost surely, 2^91000551 is an apocalyptic number.

91000551 is a deficient number, since it is larger than the sum of its proper divisors (30333521).

91000551 is a wasteful number, since it uses less digits than its factorization.

91000551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30333520.

The product of its (nonzero) digits is 225, while the sum is 21.

The square root of 91000551 is about 9539.4208943730. The cubic root of 91000551 is about 449.7950523520.

The spelling of 91000551 in words is "ninety-one million, five hundred fifty-one", and thus it is an aban number.