20989651 has 2 divisors, whose sum is σ = 20989652. Its totient is φ = 20989650.

The previous prime is 20989627. The next prime is 20989711. The reversal of 20989651 is 15698902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20989651 - 2⁷ = 20989523 is a prime.

It is not a weakly prime, because it can be changed into another prime (20989601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494825 + 10494826.

It is an arithmetic number, because the mean of its divisors is an integer number (10494826).

Almost surely, 2^20989651 is an apocalyptic number.

20989651 is a deficient number, since it is larger than the sum of its proper divisors (1).

20989651 is an equidigital number, since it uses as much as digits as its factorization.

20989651 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 20989651 is about 4581.4463873323. The cubic root of 20989651 is about 275.8470893876.

The spelling of 20989651 in words is "twenty million, nine hundred eighty-nine thousand, six hundred fifty-one".