21471261 has 12 divisors (see below), whose sum is σ = 33302592. Its totient is φ = 12269208.

The previous prime is 21471257. The next prime is 21471283. The reversal of 21471261 is 16217412.

It is not a de Polignac number, because 21471261 - 2² = 21471257 is a prime.

It is a super-2 number, since 2×21471261² = 922030097860242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21471661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 72885 + ... + 73178.

It is an arithmetic number, because the mean of its divisors is an integer number (2775216).

Almost surely, 2^21471261 is an apocalyptic number.

21471261 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21471261 is a deficient number, since it is larger than the sum of its proper divisors (11831331).

21471261 is a wasteful number, since it uses less digits than its factorization.

21471261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146080 (or 146073 counting only the distinct ones).

The product of its digits is 672, while the sum is 24.

The square root of 21471261 is about 4633.7092053775. The cubic root of 21471261 is about 277.9409368512.

Adding to 21471261 its reverse (16217412), we get a palindrome (37688673).

The spelling of 21471261 in words is "twenty-one million, four hundred seventy-one thousand, two hundred sixty-one".