20722421 has 2 divisors, whose sum is σ = 20722422. Its totient is φ = 20722420.

The previous prime is 20722409. The next prime is 20722433. The reversal of 20722421 is 12422702.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (20722409) and next prime (20722433).

It can be written as a sum of positive squares in only one way, i.e., 16564900 + 4157521 = 4070^2 + 2039^2 .

It is a cyclic number.

It is not a de Polignac number, because 20722421 - 2¹⁰ = 20721397 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20722393 and 20722402.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20722451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10361210 + 10361211.

It is an arithmetic number, because the mean of its divisors is an integer number (10361211).

Almost surely, 2^20722421 is an apocalyptic number.

It is an amenable number.

20722421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20722421 is an equidigital number, since it uses as much as digits as its factorization.

20722421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 20.

The square root of 20722421 is about 4552.1885945114. The cubic root of 20722421 is about 274.6714356937.

The spelling of 20722421 in words is "twenty million, seven hundred twenty-two thousand, four hundred twenty-one".