393744649 has 3 divisors (see below), whose sum is σ = 393764493. Its totient is φ = 393724806.

The previous prime is 393744647. The next prime is 393744721. The reversal of 393744649 is 946447393.

It is a happy number.

The square root of 393744649 is 19843.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 946447393 = 29 ⋅32636117.

It is not a de Polignac number, because 393744649 - 2¹ = 393744647 is a prime.

It is a super-2 number, since 2×393744649² = 310069697232266402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (393744641) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 9922 + ... + 29764.

It is an arithmetic number, because the mean of its divisors is an integer number (131254831).

Almost surely, 2^393744649 is an apocalyptic number.

393744649 is the 19843-rd square number.

393744649 is the 9922-nd centered octagonal number.

It is an amenable number.

393744649 is a deficient number, since it is larger than the sum of its proper divisors (19844).

393744649 is an frugal number, since it uses more digits than its factorization.

393744649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39686 (or 19843 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 49.

The cubic root of 393744649 is about 732.9452842057.

Multiplying 393744649 by its sum of digits (49), we get a square (19293487801 = 138901²).

The spelling of 393744649 in words is "three hundred ninety-three million, seven hundred forty-four thousand, six hundred forty-nine".