66139554 has 64 divisors (see below), whose sum is σ = 155796480. Its totient is φ = 18524160.

The previous prime is 66139529. The next prime is 66139583. The reversal of 66139554 is 45593166.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40302 + ... + 41910.

It is an arithmetic number, because the mean of its divisors is an integer number (2434320).

Almost surely, 2^66139554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66139554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77898240).

66139554 is an abundant number, since it is smaller than the sum of its proper divisors (89656926).

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

66139554 is a wasteful number, since it uses less digits than its factorization.

66139554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1675.

The product of its digits is 97200, while the sum is 39.

The square root of 66139554 is about 8132.6228241570. The cubic root of 66139554 is about 404.4086354859.

The spelling of 66139554 in words is "sixty-six million, one hundred thirty-nine thousand, five hundred fifty-four".