31389666 has 32 divisors (see below), whose sum is σ = 78271488. Its totient is φ = 8153040.

The previous prime is 31389661. The next prime is 31389671. The reversal of 31389666 is 66698313.

It is an interprime number because it is at equal distance from previous prime (31389661) and next prime (31389671).

It is a super-2 number, since 2×31389666² = 1970622263183112, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (31389661) 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, 33510 + ... + 34433.

It is an arithmetic number, because the mean of its divisors is an integer number (2445984).

Almost surely, 2^31389666 is an apocalyptic number.

31389666 is an abundant number, since it is smaller than the sum of its proper divisors (46881822).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31389666 is a wasteful number, since it uses less digits than its factorization.

31389666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67966.

The product of its digits is 139968, while the sum is 42.

The square root of 31389666 is about 5602.6481238786. The cubic root of 31389666 is about 315.4488134875.

The spelling of 31389666 in words is "thirty-one million, three hundred eighty-nine thousand, six hundred sixty-six".