20721479 has 2 divisors, whose sum is σ = 20721480. Its totient is φ = 20721478.

The previous prime is 20721461. The next prime is 20721497. The reversal of 20721479 is 97412702.

Together with next prime (20721497) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (20721461) and next prime (20721497).

It is a cyclic number.

It is not a de Polignac number, because 20721479 - 2⁸ = 20721223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20721439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10360739 + 10360740.

It is an arithmetic number, because the mean of its divisors is an integer number (10360740).

Almost surely, 2^20721479 is an apocalyptic number.

20721479 is a deficient number, since it is larger than the sum of its proper divisors (1).

20721479 is an equidigital number, since it uses as much as digits as its factorization.

20721479 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 20721479 is about 4552.0851266205. The cubic root of 20721479 is about 274.6672736251.

The spelling of 20721479 in words is "twenty million, seven hundred twenty-one thousand, four hundred seventy-nine".