21356257663461 has 16 divisors (see below), whose sum is σ = 33592638783488. Its totient is φ = 11809912071600.

The previous prime is 21356257663459. The next prime is 21356257663463. The reversal of 21356257663461 is 16436675265312.

It is an interprime number because it is at equal distance from previous prime (21356257663459) and next prime (21356257663463).

It is not a de Polignac number, because 21356257663461 - 2¹ = 21356257663459 is a prime.

It is a super-2 number, since 2×21356257663461² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356257663463) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16402655005 + ... + 16402656306.

It is an arithmetic number, because the mean of its divisors is an integer number (2099539923968).

Almost surely, 2^{21356257663461} is an apocalyptic number.

21356257663461 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21356257663461 is a deficient number, since it is larger than the sum of its proper divisors (12236381120027).

21356257663461 is a wasteful number, since it uses less digits than its factorization.

21356257663461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32805311352.

The product of its digits is 32659200, while the sum is 57.

The spelling of 21356257663461 in words is "twenty-one trillion, three hundred fifty-six billion, two hundred fifty-seven million, six hundred sixty-three thousand, four hundred sixty-one".