385221721 has 4 divisors (see below), whose sum is σ = 388822032. Its totient is φ = 381621412.

The previous prime is 385221709. The next prime is 385221731. The reversal of 385221721 is 127122583.

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.

It is a cyclic number.

It is not a de Polignac number, because 385221721 - 2⁹ = 385221209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (385221701) 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, 1799995 + ... + 1800208.

It is an arithmetic number, because the mean of its divisors is an integer number (97205508).

Almost surely, 2^385221721 is an apocalyptic number.

It is an amenable number.

385221721 is a deficient number, since it is larger than the sum of its proper divisors (3600311).

385221721 is a wasteful number, since it uses less digits than its factorization.

385221721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3600310.

The product of its digits is 6720, while the sum is 31.

The square root of 385221721 is about 19627.0660313762. The cubic root of 385221721 is about 727.6182594131.

The spelling of 385221721 in words is "three hundred eighty-five million, two hundred twenty-one thousand, seven hundred twenty-one".