66531387 has 32 divisors (see below), whose sum is σ = 105573888. Its totient is φ = 36850176.

The previous prime is 66531383. The next prime is 66531391. The reversal of 66531387 is 78313566.

It is an interprime number because it is at equal distance from previous prime (66531383) and next prime (66531391).

It is not a de Polignac number, because 66531387 - 2² = 66531383 is a prime.

It is a super-2 number, since 2×66531387² = 8852850912287538, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (66531383) 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, 13068 + ... + 17430.

It is an arithmetic number, because the mean of its divisors is an integer number (3299184).

Almost surely, 2^66531387 is an apocalyptic number.

66531387 is a deficient number, since it is larger than the sum of its proper divisors (39042501).

66531387 is a wasteful number, since it uses less digits than its factorization.

66531387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4419.

The product of its digits is 90720, while the sum is 39.

The square root of 66531387 is about 8156.6774485694. The cubic root of 66531387 is about 405.2056812295.

The spelling of 66531387 in words is "sixty-six million, five hundred thirty-one thousand, three hundred eighty-seven".