20661658 has 8 divisors (see below), whose sum is σ = 31012020. Its totient is φ = 10324320.

The previous prime is 20661643. The next prime is 20661689. The reversal of 20661658 is 85616602.

It can be written as a sum of positive squares in 2 ways, for example, as 20548089 + 113569 = 4533^2 + 337^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×20661658² = 853808222617928, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3598 + ... + 7366.

Almost surely, 2^20661658 is an apocalyptic number.

20661658 is a deficient number, since it is larger than the sum of its proper divisors (10350362).

20661658 is a wasteful number, since it uses less digits than its factorization.

20661658 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6512.

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 20661658 is about 4545.5096523932. The cubic root of 20661658 is about 274.4027058328.

The spelling of 20661658 in words is "twenty million, six hundred sixty-one thousand, six hundred fifty-eight".