664293981 has 32 divisors (see below), whose sum is σ = 1029692160. Its totient is φ = 377524224.

The previous prime is 664293943. The next prime is 664293983. The reversal of 664293981 is 189392466.

664293981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 664293981 - 2¹³ = 664285789 is a prime.

It is a super-2 number, since 2×664293981² = 882572986385656722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 664293981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664293983) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13245 + ... + 38781.

It is an arithmetic number, because the mean of its divisors is an integer number (32177880).

Almost surely, 2^664293981 is an apocalyptic number.

It is an amenable number.

664293981 is a deficient number, since it is larger than the sum of its proper divisors (365398179).

664293981 is a wasteful number, since it uses less digits than its factorization.

664293981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25605.

The product of its digits is 559872, while the sum is 48.

The square root of 664293981 is about 25773.9011598943. The cubic root of 664293981 is about 872.5428668906.

The spelling of 664293981 in words is "six hundred sixty-four million, two hundred ninety-three thousand, nine hundred eighty-one".