21401757 has 12 divisors (see below), whose sum is σ = 33291804. Its totient is φ = 13170240.

The previous prime is 21401717. The next prime is 21401761. The reversal of 21401757 is 75710412.

It can be written as a sum of positive squares in 2 ways, for example, as 6610041 + 14791716 = 2571^2 + 3846^2 .

It is not a de Polignac number, because 21401757 - 2⁶ = 21401693 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21401757.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401717) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 91344 + ... + 91577.

It is an arithmetic number, because the mean of its divisors is an integer number (2774317).

Almost surely, 2^21401757 is an apocalyptic number.

It is an amenable number.

21401757 is a deficient number, since it is larger than the sum of its proper divisors (11890047).

21401757 is a wasteful number, since it uses less digits than its factorization.

21401757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182940 (or 182937 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 27.

The square root of 21401757 is about 4626.2033029256. The cubic root of 21401757 is about 277.6407077989.

The spelling of 21401757 in words is "twenty-one million, four hundred one thousand, seven hundred fifty-seven".