20721554 has 32 divisors (see below), whose sum is σ = 36917760. Its totient is φ = 8538048.

The previous prime is 20721553. The next prime is 20721583. The reversal of 20721554 is 45512702.

It is not an unprimeable number, because it can be changed into a prime (20721553) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 56279 + ... + 56645.

It is an arithmetic number, because the mean of its divisors is an integer number (1153680).

Almost surely, 2^20721554 is an apocalyptic number.

20721554 is a deficient number, since it is larger than the sum of its proper divisors (16196206).

20721554 is a wasteful number, since it uses less digits than its factorization.

20721554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522.

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 20721554 is about 4552.0933645961. The cubic root of 20721554 is about 274.6676050046.

The spelling of 20721554 in words is "twenty million, seven hundred twenty-one thousand, five hundred fifty-four".