21401549 has 8 divisors (see below), whose sum is σ = 23610552. Its totient is φ = 19272960.

The previous prime is 21401539. The next prime is 21401557. The reversal of 21401549 is 94510412.

It can be written as a sum of positive squares in 4 ways, for example, as 75625 + 21325924 = 275^2 + 4618^2 .

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 21401549 - 2²⁰ = 20352973 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401539) 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, 19544 + ... + 20609.

It is an arithmetic number, because the mean of its divisors is an integer number (2951319).

Almost surely, 2^21401549 is an apocalyptic number.

It is an amenable number.

21401549 is a deficient number, since it is larger than the sum of its proper divisors (2209003).

21401549 is a wasteful number, since it uses less digits than its factorization.

21401549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40207.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21401549 is about 4626.1808222334. The cubic root of 21401549 is about 277.6398083485.

The spelling of 21401549 in words is "twenty-one million, four hundred one thousand, five hundred forty-nine".