66438801 has 81 divisors (see below), whose sum is σ = 120551067. Its totient is φ = 35212320.

The previous prime is 66438793. The next prime is 66438809. The reversal of 66438801 is 10883466.

It is a happy number.

The square root of 66438801 is 8151.

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

66438801 is a `hidden beast` number, since 6 + 643 + 8 + 8 + 0 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (66438793) and next prime (66438809).

It can be written as a sum of positive squares in only one way, i.e., 9828225 + 56610576 = 3135^2 + 7524^2 .

It is not a de Polignac number, because 66438801 - 2³ = 66438793 is a prime.

It is a super-2 number, since 2×66438801² = 8828228556635202, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66438809) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 3496770 + ... + 3496788.

Almost surely, 2^66438801 is an apocalyptic number.

66438801 is the 8151-st square number.

66438801 is the 4076-th centered octagonal number.

It is an amenable number.

66438801 is a deficient number, since it is larger than the sum of its proper divisors (54112266).

66438801 is a wasteful number, since it uses less digits than its factorization.

66438801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The cubic root of 66438801 is about 405.0176306911.

Multiplying 66438801 by its sum of digits (36), we get a square (2391796836 = 48906²).

The spelling of 66438801 in words is "sixty-six million, four hundred thirty-eight thousand, eight hundred one".