20721453 has 16 divisors (see below), whose sum is σ = 29362176. Its totient is φ = 12953600.

The previous prime is 20721439. The next prime is 20721461. The reversal of 20721453 is 35412702.

It is a cyclic number.

It is not a de Polignac number, because 20721453 - 2¹⁰ = 20720429 is a prime.

It is a super-2 number, since 2×20721453² = 858757228862418, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20721433) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17428 + ... + 18578.

It is an arithmetic number, because the mean of its divisors is an integer number (1835136).

Almost surely, 2^20721453 is an apocalyptic number.

It is an amenable number.

20721453 is a deficient number, since it is larger than the sum of its proper divisors (8640723).

20721453 is a wasteful number, since it uses less digits than its factorization.

20721453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1524.

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 20721453 is about 4552.0822707855. The cubic root of 20721453 is about 274.6671587467.

The spelling of 20721453 in words is "twenty million, seven hundred twenty-one thousand, four hundred fifty-three".