21876961 has 6 divisors (see below), whose sum is σ = 23089362. Its totient is φ = 20725200.

The previous prime is 21876947. The next prime is 21876973. The reversal of 21876961 is 16967812.

It can be written as a sum of positive squares in only one way, i.e., 21669025 + 207936 = 4655^2 + 456^2 .

It is not a de Polignac number, because 21876961 - 2¹¹ = 21874913 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21876901) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 29940 + ... + 30661.

It is an arithmetic number, because the mean of its divisors is an integer number (3848227).

Almost surely, 2^21876961 is an apocalyptic number.

It is an amenable number.

21876961 is a deficient number, since it is larger than the sum of its proper divisors (1212401).

21876961 is an equidigital number, since it uses as much as digits as its factorization.

21876961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60639 (or 60620 counting only the distinct ones).

The product of its digits is 36288, while the sum is 40.

The square root of 21876961 is about 4677.2813684875. The cubic root of 21876961 is about 279.6805924097.

The spelling of 21876961 in words is "twenty-one million, eight hundred seventy-six thousand, nine hundred sixty-one".