21276961 has 4 divisors (see below), whose sum is σ = 21852052. Its totient is φ = 20701872.

The previous prime is 21276953. The next prime is 21276973. The reversal of 21276961 is 16967212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11943936 + 9333025 = 3456^2 + 3055^2 .

It is a cyclic number.

It is not a de Polignac number, because 21276961 - 2³ = 21276953 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21276461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 287490 + ... + 287563.

It is an arithmetic number, because the mean of its divisors is an integer number (5463013).

Almost surely, 2^21276961 is an apocalyptic number.

It is an amenable number.

21276961 is a deficient number, since it is larger than the sum of its proper divisors (575091).

21276961 is an equidigital number, since it uses as much as digits as its factorization.

21276961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 575090.

The product of its digits is 9072, while the sum is 34.

The square root of 21276961 is about 4612.6956327076. The cubic root of 21276961 is about 277.1000042934.

The spelling of 21276961 in words is "twenty-one million, two hundred seventy-six thousand, nine hundred sixty-one".