90789649921 has 2 divisors, whose sum is σ = 90789649922. Its totient is φ = 90789649920.

The previous prime is 90789649889. The next prime is 90789649927. The reversal of 90789649921 is 12994698709.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69506049600 + 21283600321 = 263640^2 + 145889^2 .

It is a cyclic number.

It is not a de Polignac number, because 90789649921 - 2⁵ = 90789649889 is a prime.

It is not a weakly prime, because it can be changed into another prime (90789649927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45394824960 + 45394824961.

It is an arithmetic number, because the mean of its divisors is an integer number (45394824961).

Almost surely, 2^90789649921 is an apocalyptic number.

It is an amenable number.

90789649921 is a deficient number, since it is larger than the sum of its proper divisors (1).

90789649921 is an equidigital number, since it uses as much as digits as its factorization.

90789649921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17635968, while the sum is 64.

The spelling of 90789649921 in words is "ninety billion, seven hundred eighty-nine million, six hundred forty-nine thousand, nine hundred twenty-one".