66021638 has 16 divisors (see below), whose sum is σ = 104759136. Its totient is φ = 31141440.

The previous prime is 66021629. The next prime is 66021647. The reversal of 66021638 is 83612066.

It is an interprime number because it is at equal distance from previous prime (66021629) and next prime (66021647).

It is a super-3 number, since 3×66021638³ (a number of 24 digits) contains 333 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6473 + ... + 13188.

It is an arithmetic number, because the mean of its divisors is an integer number (6547446).

Almost surely, 2^66021638 is an apocalyptic number.

66021638 is a deficient number, since it is larger than the sum of its proper divisors (38737498).

66021638 is a wasteful number, since it uses less digits than its factorization.

66021638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19759.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 66021638 is about 8125.3700223436. The cubic root of 66021638 is about 404.1681610507.

The spelling of 66021638 in words is "sixty-six million, twenty-one thousand, six hundred thirty-eight".