20951989 has 8 divisors (see below), whose sum is σ = 21466368. Its totient is φ = 20440560.

The previous prime is 20951981. The next prime is 20951993. The reversal of 20951989 is 98915902.

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

It is a cyclic number.

It is not a de Polignac number, because 20951989 - 2³ = 20951981 is a prime.

It is a super-2 number, since 2×20951989² = 877971686112242, 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 (20951981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21184 + ... + 22150.

It is an arithmetic number, because the mean of its divisors is an integer number (2683296).

Almost surely, 2^20951989 is an apocalyptic number.

It is an amenable number.

20951989 is a deficient number, since it is larger than the sum of its proper divisors (514379).

20951989 is an equidigital number, since it uses as much as digits as its factorization.

20951989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1475.

The product of its (nonzero) digits is 58320, while the sum is 43.

The square root of 20951989 is about 4577.3342678900. The cubic root of 20951989 is about 275.6820052872.

The spelling of 20951989 in words is "twenty million, nine hundred fifty-one thousand, nine hundred eighty-nine".