21400720254381 has 64 divisors (see below), whose sum is σ = 33474398791680. Its totient is φ = 12046661003520.

The previous prime is 21400720254379. The next prime is 21400720254467. The reversal of 21400720254381 is 18345202700412.

It is a happy number.

It is not a de Polignac number, because 21400720254381 - 2¹ = 21400720254379 is a prime.

It is a super-2 number, since 2×21400720254381² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400720254371) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 612376 + ... + 6570878.

It is an arithmetic number, because the mean of its divisors is an integer number (523037481120).

Almost surely, 2^{21400720254381} is an apocalyptic number.

It is an amenable number.

21400720254381 is a deficient number, since it is larger than the sum of its proper divisors (12073678537299).

21400720254381 is a wasteful number, since it uses less digits than its factorization.

21400720254381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5958706.

The product of its (nonzero) digits is 107520, while the sum is 39.

Adding to 21400720254381 its reverse (18345202700412), we get a palindrome (39745922954793).

The spelling of 21400720254381 in words is "twenty-one trillion, four hundred billion, seven hundred twenty million, two hundred fifty-four thousand, three hundred eighty-one".