20783621 has 2 divisors, whose sum is σ = 20783622. Its totient is φ = 20783620.

The previous prime is 20783561. The next prime is 20783627. The reversal of 20783621 is 12638702.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12859396 + 7924225 = 3586^2 + 2815^2 .

It is a cyclic number.

It is not a de Polignac number, because 20783621 - 2²² = 16589317 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20783627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10391810 + 10391811.

It is an arithmetic number, because the mean of its divisors is an integer number (10391811).

Almost surely, 2^20783621 is an apocalyptic number.

It is an amenable number.

20783621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20783621 is an equidigital number, since it uses as much as digits as its factorization.

20783621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 20783621 is about 4558.9056800947. The cubic root of 20783621 is about 274.9415677504.

The spelling of 20783621 in words is "twenty million, seven hundred eighty-three thousand, six hundred twenty-one".