21404010021 has 16 divisors (see below), whose sum is σ = 30226219200. Its totient is φ = 13426059008.

The previous prime is 21404009989. The next prime is 21404010053. The reversal of 21404010021 is 12001040412.

It is an interprime number because it is at equal distance from previous prime (21404009989) and next prime (21404010053).

It is a cyclic number.

It is not a de Polignac number, because 21404010021 - 2⁵ = 21404009989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404010721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 121195 + ... + 239783.

It is an arithmetic number, because the mean of its divisors is an integer number (1889138700).

Almost surely, 2^21404010021 is an apocalyptic number.

It is an amenable number.

21404010021 is a deficient number, since it is larger than the sum of its proper divisors (8822209179).

21404010021 is a wasteful number, since it uses less digits than its factorization.

21404010021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122148.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21404010021 its reverse (12001040412), we get a palindrome (33405050433).

The spelling of 21404010021 in words is "twenty-one billion, four hundred four million, ten thousand, twenty-one".