20646989 has 4 divisors (see below), whose sum is σ = 22524000. Its totient is φ = 18769980.

The previous prime is 20646973. The next prime is 20647001. The reversal of 20646989 is 98964602.

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 not a de Polignac number, because 20646989 - 2⁴ = 20646973 is a prime.

It is a super-2 number, since 2×20646989² = 852596309532242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20646929) 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, 938489 + ... + 938510.

It is an arithmetic number, because the mean of its divisors is an integer number (5631000).

Almost surely, 2^20646989 is an apocalyptic number.

It is an amenable number.

20646989 is a deficient number, since it is larger than the sum of its proper divisors (1877011).

20646989 is a wasteful number, since it uses less digits than its factorization.

20646989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1877010.

The product of its (nonzero) digits is 186624, while the sum is 44.

The square root of 20646989 is about 4543.8957954601. The cubic root of 20646989 is about 274.3377519256.

The spelling of 20646989 in words is "twenty million, six hundred forty-six thousand, nine hundred eighty-nine".