21461643 has 12 divisors (see below), whose sum is σ = 35428848. Its totient is φ = 12263760.

The previous prime is 21461617. The next prime is 21461647. The reversal of 21461643 is 34616412.

21461643 is a `hidden beast` number, since 2 + 1 + 4 + 616 + 43 = 666.

It is not a de Polignac number, because 21461643 - 2⁵ = 21461611 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21461647) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 170268 + ... + 170393.

It is an arithmetic number, because the mean of its divisors is an integer number (2952404).

Almost surely, 2^21461643 is an apocalyptic number.

21461643 is a deficient number, since it is larger than the sum of its proper divisors (13967205).

21461643 is a wasteful number, since it uses less digits than its factorization.

21461643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340674 (or 340671 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 21461643 is about 4632.6712596514. The cubic root of 21461643 is about 277.8994296604.

The spelling of 21461643 in words is "twenty-one million, four hundred sixty-one thousand, six hundred forty-three".