20961281 has 8 divisors (see below), whose sum is σ = 22919328. Its totient is φ = 19012000.

The previous prime is 20961263. The next prime is 20961299. The reversal of 20961281 is 18216902.

It is an interprime number because it is at equal distance from previous prime (20961263) and next prime (20961299).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20961281 is a prime.

It is a super-2 number, since 2×20961281² = 878750602321922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20961251) 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, 3461 + ... + 7341.

It is an arithmetic number, because the mean of its divisors is an integer number (2864916).

Almost surely, 2^20961281 is an apocalyptic number.

20961281 is the 2048-th centered decagonal number.

It is an amenable number.

20961281 is a deficient number, since it is larger than the sum of its proper divisors (1958047).

20961281 is a wasteful number, since it uses less digits than its factorization.

20961281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4383.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 20961281 is about 4578.3491566284. The cubic root of 20961281 is about 275.7227533453.

The spelling of 20961281 in words is "twenty million, nine hundred sixty-one thousand, two hundred eighty-one".