21142961 has 18 divisors (see below), whose sum is σ = 25470450. Its totient is φ = 17498880.

The previous prime is 21142939. The next prime is 21142963. The reversal of 21142961 is 16924112.

It can be written as a sum of positive squares in only one way, i.e., 18835600 + 2307361 = 4340^2 + 1519^2 .

It is not a de Polignac number, because 21142961 - 2⁶ = 21142897 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21142961.

It is not an unprimeable number, because it can be changed into a prime (21142963) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 46865 + ... + 47313.

It is an arithmetic number, because the mean of its divisors is an integer number (1415025).

Almost surely, 2^21142961 is an apocalyptic number.

It is an amenable number.

21142961 is a deficient number, since it is larger than the sum of its proper divisors (4327489).

21142961 is an equidigital number, since it uses as much as digits as its factorization.

21142961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525 (or 487 counting only the distinct ones).

The product of its digits is 864, while the sum is 26.

The square root of 21142961 is about 4598.1475617905. The cubic root of 21142961 is about 276.5170635199.

The spelling of 21142961 in words is "twenty-one million, one hundred forty-two thousand, nine hundred sixty-one".