90159493721 has 4 divisors (see below), whose sum is σ = 98355811344. Its totient is φ = 81963176100.

The previous prime is 90159493717. The next prime is 90159493733. The reversal of 90159493721 is 12739495109.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12739495109 = 11 ⋅1158135919.

It is a cyclic number.

It is not a de Polignac number, because 90159493721 - 2² = 90159493717 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 90159493721.

It is not an unprimeable number, because it can be changed into a prime (90159403721) 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, 4098158795 + ... + 4098158816.

It is an arithmetic number, because the mean of its divisors is an integer number (24588952836).

Almost surely, 2^90159493721 is an apocalyptic number.

It is an amenable number.

90159493721 is a deficient number, since it is larger than the sum of its proper divisors (8196317623).

90159493721 is a wasteful number, since it uses less digits than its factorization.

90159493721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8196317622.

The product of its (nonzero) digits is 612360, while the sum is 50.

The spelling of 90159493721 in words is "ninety billion, one hundred fifty-nine million, four hundred ninety-three thousand, seven hundred twenty-one".