669649381 has 4 divisors (see below), whose sum is σ = 670711264. Its totient is φ = 668587500.

The previous prime is 669649339. The next prime is 669649391. The reversal of 669649381 is 183946966.

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 669649381 - 2¹¹ = 669647333 is a prime.

It is a super-2 number, since 2×669649381² = 896860586947366322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (669649391) 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, 529995 + ... + 531256.

It is an arithmetic number, because the mean of its divisors is an integer number (167677816).

Almost surely, 2^669649381 is an apocalyptic number.

It is an amenable number.

669649381 is a deficient number, since it is larger than the sum of its proper divisors (1061883).

669649381 is a wasteful number, since it uses less digits than its factorization.

669649381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1061882.

The product of its digits is 1679616, while the sum is 52.

The square root of 669649381 is about 25877.5845279269. The cubic root of 669649381 is about 874.8813470675.

The spelling of 669649381 in words is "six hundred sixty-nine million, six hundred forty-nine thousand, three hundred eighty-one".