21538773 has 24 divisors (see below), whose sum is σ = 32438016. Its totient is φ = 13759200.

The previous prime is 21538757. The next prime is 21538789. The reversal of 21538773 is 37783512.

It is an interprime number because it is at equal distance from previous prime (21538757) and next prime (21538789).

It is not a de Polignac number, because 21538773 - 2⁴ = 21538757 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21538703) 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 23 ways as a sum of consecutive naturals, for example, 23188 + ... + 24098.

It is an arithmetic number, because the mean of its divisors is an integer number (1351584).

Almost surely, 2^21538773 is an apocalyptic number.

It is an amenable number.

21538773 is a deficient number, since it is larger than the sum of its proper divisors (10899243).

21538773 is a wasteful number, since it uses less digits than its factorization.

21538773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1025 (or 1022 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 21538773 is about 4640.9883645620. The cubic root of 21538773 is about 278.2319415873.

The spelling of 21538773 in words is "twenty-one million, five hundred thirty-eight thousand, seven hundred seventy-three".