399136221 has 16 divisors (see below), whose sum is σ = 645069120. Its totient is φ = 241900560.

The previous prime is 399136201. The next prime is 399136229. The reversal of 399136221 is 122631993.

It is a happy number.

It is not a de Polignac number, because 399136221 - 2²² = 394941917 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399136229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 671650 + ... + 672243.

It is an arithmetic number, because the mean of its divisors is an integer number (40316820).

Almost surely, 2^399136221 is an apocalyptic number.

It is an amenable number.

399136221 is a deficient number, since it is larger than the sum of its proper divisors (245932899).

399136221 is a wasteful number, since it uses less digits than its factorization.

399136221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1343913 (or 1343907 counting only the distinct ones).

The product of its digits is 17496, while the sum is 36.

The square root of 399136221 is about 19978.3938543618. The cubic root of 399136221 is about 736.2755526638.

The spelling of 399136221 in words is "three hundred ninety-nine million, one hundred thirty-six thousand, two hundred twenty-one".