90840521 has 2 divisors, whose sum is σ = 90840522. Its totient is φ = 90840520.

The previous prime is 90840517. The next prime is 90840523. The reversal of 90840521 is 12504809.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76125625 + 14714896 = 8725^2 + 3836^2 .

It is a cyclic number.

It is not a de Polignac number, because 90840521 - 2² = 90840517 is a prime.

Together with 90840523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (90840523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45420260 + 45420261.

It is an arithmetic number, because the mean of its divisors is an integer number (45420261).

Almost surely, 2^90840521 is an apocalyptic number.

It is an amenable number.

90840521 is a deficient number, since it is larger than the sum of its proper divisors (1).

90840521 is an equidigital number, since it uses as much as digits as its factorization.

90840521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 90840521 is about 9531.0293777745. The cubic root of 90840521 is about 449.5312336650.

The spelling of 90840521 in words is "ninety million, eight hundred forty thousand, five hundred twenty-one".