90423821 has 2 divisors, whose sum is σ = 90423822. Its totient is φ = 90423820.

The previous prime is 90423791. The next prime is 90423857. The reversal of 90423821 is 12832409.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69538921 + 20884900 = 8339^2 + 4570^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-90423821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90423521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45211910 + 45211911.

It is an arithmetic number, because the mean of its divisors is an integer number (45211911).

Almost surely, 2^90423821 is an apocalyptic number.

It is an amenable number.

90423821 is a deficient number, since it is larger than the sum of its proper divisors (1).

90423821 is an equidigital number, since it uses as much as digits as its factorization.

90423821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 90423821 is about 9509.1440729437. The cubic root of 90423821 is about 448.8428227483.

The spelling of 90423821 in words is "ninety million, four hundred twenty-three thousand, eight hundred twenty-one".