21415261 has 8 divisors (see below), whose sum is σ = 25762880. Its totient is φ = 17389728.

The previous prime is 21415249. The next prime is 21415307. The reversal of 21415261 is 16251412.

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 21415261 - 2⁷ = 21415133 is a prime.

It is a super-2 number, since 2×21415261² = 917226807396242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21415211) 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 7 ways as a sum of consecutive naturals, for example, 80376 + ... + 80641.

It is an arithmetic number, because the mean of its divisors is an integer number (3220360).

Almost surely, 2^21415261 is an apocalyptic number.

It is an amenable number.

21415261 is a deficient number, since it is larger than the sum of its proper divisors (4347619).

21415261 is a wasteful number, since it uses less digits than its factorization.

21415261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161043.

The product of its digits is 480, while the sum is 22.

The square root of 21415261 is about 4627.6625849342. The cubic root of 21415261 is about 277.6990904172.

Adding to 21415261 its reverse (16251412), we get a palindrome (37666673).

The spelling of 21415261 in words is "twenty-one million, four hundred fifteen thousand, two hundred sixty-one".