20975661 has 12 divisors (see below), whose sum is σ = 34626592. Its totient is φ = 11986056.

The previous prime is 20975657. The next prime is 20975663. The reversal of 20975661 is 16657902.

20975661 is a `hidden beast` number, since 2 + 0 + 97 + 566 + 1 = 666.

It is not a de Polignac number, because 20975661 - 2² = 20975657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20975663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166411 + ... + 166536.

Almost surely, 2^20975661 is an apocalyptic number.

20975661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20975661 is a deficient number, since it is larger than the sum of its proper divisors (13650931).

20975661 is a wasteful number, since it uses less digits than its factorization.

20975661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332960 (or 332957 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 20975661 is about 4579.9193224335. The cubic root of 20975661 is about 275.7857899963.

The spelling of 20975661 in words is "twenty million, nine hundred seventy-five thousand, six hundred sixty-one".