20721450 has 24 divisors (see below), whose sum is σ = 51389568. Its totient is φ = 5525680.

The previous prime is 20721439. The next prime is 20721461. The reversal of 20721450 is 5412702.

It is an interprime number because it is at equal distance from previous prime (20721439) and next prime (20721461).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 68922 + ... + 69221.

It is an arithmetic number, because the mean of its divisors is an integer number (2141232).

Almost surely, 2^20721450 is an apocalyptic number.

20721450 is an abundant number, since it is smaller than the sum of its proper divisors (30668118).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20721450 is a wasteful number, since it uses less digits than its factorization.

20721450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138158 (or 138153 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 20721450 is about 4552.0819412660. The cubic root of 20721450 is about 274.6671454915.

The spelling of 20721450 in words is "twenty million, seven hundred twenty-one thousand, four hundred fifty".