21502355505451 has 4 divisors (see below), whose sum is σ = 21548998359504. Its totient is φ = 21455712651400.

The previous prime is 21502355505443. The next prime is 21502355505481. The reversal of 21502355505451 is 15450555320512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21502355505451 - 2³ = 21502355505443 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21502355505398 and 21502355505407.

It is not an unprimeable number, because it can be changed into a prime (21502355505481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23321426335 + ... + 23321427256.

It is an arithmetic number, because the mean of its divisors is an integer number (5387249589876).

Almost surely, 2^{21502355505451} is an apocalyptic number.

21502355505451 is a deficient number, since it is larger than the sum of its proper divisors (46642854053).

21502355505451 is an equidigital number, since it uses as much as digits as its factorization.

21502355505451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46642854052.

The product of its (nonzero) digits is 750000, while the sum is 43.

The spelling of 21502355505451 in words is "twenty-one trillion, five hundred two billion, three hundred fifty-five million, five hundred five thousand, four hundred fifty-one".