85721905 has 8 divisors (see below), whose sum is σ = 108917352. Its totient is φ = 64543488.

The previous prime is 85721903. The next prime is 85721963. The reversal of 85721905 is 50912758.

It can be written as a sum of positive squares in 4 ways, for example, as 43718544 + 42003361 = 6612^2 + 6481^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 85721905 - 2¹ = 85721903 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85721903) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 504162 + ... + 504331.

It is an arithmetic number, because the mean of its divisors is an integer number (13614669).

Almost surely, 2^85721905 is an apocalyptic number.

85721905 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

85721905 is a deficient number, since it is larger than the sum of its proper divisors (23195447).

85721905 is a wasteful number, since it uses less digits than its factorization.

85721905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1008515.

The product of its (nonzero) digits is 25200, while the sum is 37.

The square root of 85721905 is about 9258.6124770400. The cubic root of 85721905 is about 440.9242023633.

The spelling of 85721905 in words is "eighty-five million, seven hundred twenty-one thousand, nine hundred five".