90691821 has 24 divisors (see below), whose sum is σ = 151317504. Its totient is φ = 51730560.

The previous prime is 90691819. The next prime is 90691823. The reversal of 90691821 is 12819609.

It is an interprime number because it is at equal distance from previous prime (90691819) and next prime (90691823).

It is not a de Polignac number, because 90691821 - 2¹ = 90691819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90691823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25261 + ... + 28626.

It is an arithmetic number, because the mean of its divisors is an integer number (6304896).

Almost surely, 2^90691821 is an apocalyptic number.

It is an amenable number.

90691821 is a deficient number, since it is larger than the sum of its proper divisors (60625683).

90691821 is a wasteful number, since it uses less digits than its factorization.

90691821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53921 (or 53918 counting only the distinct ones).

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

The square root of 90691821 is about 9523.2253464884. The cubic root of 90691821 is about 449.2858152815.

The spelling of 90691821 in words is "ninety million, six hundred ninety-one thousand, eight hundred twenty-one".