66891401 has 4 divisors (see below), whose sum is σ = 66955392. Its totient is φ = 66827412.

The previous prime is 66891373. The next prime is 66891403. The reversal of 66891401 is 10419866.

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 66891401 - 2¹⁰ = 66890377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66891403) 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, 30401 + ... + 32526.

It is an arithmetic number, because the mean of its divisors is an integer number (16738848).

Almost surely, 2^66891401 is an apocalyptic number.

It is an amenable number.

66891401 is a deficient number, since it is larger than the sum of its proper divisors (63991).

66891401 is a wasteful number, since it uses less digits than its factorization.

66891401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63990.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 66891401 is about 8178.7163418228. The cubic root of 66891401 is about 405.9352485572.

The spelling of 66891401 in words is "sixty-six million, eight hundred ninety-one thousand, four hundred one".