21361549 has 12 divisors (see below), whose sum is σ = 24367392. Its totient is φ = 18570200.

The previous prime is 21361519. The next prime is 21361579. The reversal of 21361549 is 94516312.

It is an interprime number because it is at equal distance from previous prime (21361519) and next prime (21361579).

It is not a de Polignac number, because 21361549 - 2⁷ = 21361421 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21361549.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21361519) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3984 + ... + 7654.

It is an arithmetic number, because the mean of its divisors is an integer number (2030616).

Almost surely, 2^21361549 is an apocalyptic number.

It is an amenable number.

21361549 is a deficient number, since it is larger than the sum of its proper divisors (3005843).

21361549 is a wasteful number, since it uses less digits than its factorization.

21361549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3728 (or 3705 counting only the distinct ones).

The product of its digits is 6480, while the sum is 31.

The square root of 21361549 is about 4621.8555797428. The cubic root of 21361549 is about 277.4667286897.

The spelling of 21361549 in words is "twenty-one million, three hundred sixty-one thousand, five hundred forty-nine".