20670981 has 4 divisors (see below), whose sum is σ = 27561312. Its totient is φ = 13780652.

The previous prime is 20670959. The next prime is 20670983. The reversal of 20670981 is 18907602.

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 a de Polignac number, because none of the positive numbers 2^k-20670981 is a prime.

It is a super-2 number, since 2×20670981² = 854578911004722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20670983) 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, 3445161 + ... + 3445166.

It is an arithmetic number, because the mean of its divisors is an integer number (6890328).

Almost surely, 2^20670981 is an apocalyptic number.

It is an amenable number.

20670981 is a deficient number, since it is larger than the sum of its proper divisors (6890331).

20670981 is an equidigital number, since it uses as much as digits as its factorization.

20670981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6890330.

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 20670981 is about 4546.5350543023. The cubic root of 20670981 is about 274.4439718297.

The spelling of 20670981 in words is "twenty million, six hundred seventy thousand, nine hundred eighty-one".