21261356246451 has 16 divisors (see below), whose sum is σ = 28773212636160. Its totient is φ = 13962222335040.

The previous prime is 21261356246423. The next prime is 21261356246479. The reversal of 21261356246451 is 15464265316212.

It is an interprime number because it is at equal distance from previous prime (21261356246423) and next prime (21261356246479).

It is not a de Polignac number, because 21261356246451 - 2¹⁸ = 21261355984307 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21261356246451.

It is not an unprimeable number, because it can be changed into a prime (21261356246651) 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, 43966155 + ... + 44447108.

It is an arithmetic number, because the mean of its divisors is an integer number (1798325789760).

Almost surely, 2^{21261356246451} is an apocalyptic number.

21261356246451 is a deficient number, since it is larger than the sum of its proper divisors (7511856389709).

21261356246451 is a wasteful number, since it uses less digits than its factorization.

21261356246451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88414466.

The product of its digits is 2073600, while the sum is 48.

The spelling of 21261356246451 in words is "twenty-one trillion, two hundred sixty-one billion, three hundred fifty-six million, two hundred forty-six thousand, four hundred fifty-one".