21621405452153 has 4 divisors (see below), whose sum is σ = 23284590486948. Its totient is φ = 19958220417360.

The previous prime is 21621405452149. The next prime is 21621405452183. The reversal of 21621405452153 is 35125450412612.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11932547739904 + 9688857712249 = 3454352^2 + 3112693^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621405452153 - 2² = 21621405452149 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21621405452153.

It is not an unprimeable number, because it can be changed into a prime (21621405452113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 831592517378 + ... + 831592517403.

It is an arithmetic number, because the mean of its divisors is an integer number (5821147621737).

Almost surely, 2^{21621405452153} is an apocalyptic number.

It is an amenable number.

21621405452153 is a deficient number, since it is larger than the sum of its proper divisors (1663185034795).

21621405452153 is a wasteful number, since it uses less digits than its factorization.

21621405452153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1663185034794.

The product of its (nonzero) digits is 288000, while the sum is 41.

Adding to 21621405452153 its reverse (35125450412612), we get a palindrome (56746855864765).

The spelling of 21621405452153 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred five million, four hundred fifty-two thousand, one hundred fifty-three".