85170001921 has 9 divisors (see below), whose sum is σ = 90479978499. Its totient is φ = 80155332384.

The previous prime is 85170001919. The next prime is 85170001979. The reversal of 85170001921 is 12910007158.

It is a happy number.

The square root of 85170001921 is 291839.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 66308825025 + 18861176896 = 257505^2 + 137336^2 .

It is not a de Polignac number, because 85170001921 - 2¹ = 85170001919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85170001991) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4952680 + ... + 4969846.

Almost surely, 2^85170001921 is an apocalyptic number.

85170001921 is the 291839-th square number.

85170001921 is the 145920-th centered octagonal number.

It is an amenable number.

85170001921 is a deficient number, since it is larger than the sum of its proper divisors (5309976578).

85170001921 is an frugal number, since it uses more digits than its factorization.

85170001921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34368 (or 17184 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 34.

The spelling of 85170001921 in words is "eighty-five billion, one hundred seventy million, one thousand, nine hundred twenty-one".