85721906 has 4 divisors (see below), whose sum is σ = 128582862. Its totient is φ = 42860952.

The previous prime is 85721903. The next prime is 85721963. The reversal of 85721906 is 60912758.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 55636681 + 30085225 = 7459^2 + 5485^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 85721906.

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 as a sum of consecutive naturals, namely, 21430475 + ... + 21430478.

Almost surely, 2^85721906 is an apocalyptic number.

85721906 is a deficient number, since it is larger than the sum of its proper divisors (42860956).

85721906 is a wasteful number, since it uses less digits than its factorization.

85721906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42860955.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 85721906 is about 9258.6125310437. The cubic root of 85721906 is about 440.9242040778.

The spelling of 85721906 in words is "eighty-five million, seven hundred twenty-one thousand, nine hundred six".