21741521 has 8 divisors (see below), whose sum is σ = 23582664. Its totient is φ = 19962880.

The previous prime is 21741493. The next prime is 21741523. The reversal of 21741521 is 12514712.

It can be written as a sum of positive squares in 4 ways, for example, as 1392400 + 20349121 = 1180^2 + 4511^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21741521 - 2¹⁸ = 21479377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21741523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14900 + ... + 16293.

It is an arithmetic number, because the mean of its divisors is an integer number (2947833).

Almost surely, 2^21741521 is an apocalyptic number.

It is an amenable number.

21741521 is a deficient number, since it is larger than the sum of its proper divisors (1841143).

21741521 is a wasteful number, since it uses less digits than its factorization.

21741521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31251.

The product of its digits is 560, while the sum is 23.

The square root of 21741521 is about 4662.7803937136. The cubic root of 21741521 is about 279.1022308352.

The spelling of 21741521 in words is "twenty-one million, seven hundred forty-one thousand, five hundred twenty-one".