20510253400661 has 4 divisors (see below), whose sum is σ = 20510668713024. Its totient is φ = 20509838088300.

The previous prime is 20510253400631. The next prime is 20510253400753. The reversal of 20510253400661 is 16600435201502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20510253400661 - 2¹⁰ = 20510253399637 is a prime.

It is a super-2 number, since 2×20510253400661² (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 (20510253400621) 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, 207582095 + ... + 207680876.

It is an arithmetic number, because the mean of its divisors is an integer number (5127667178256).

Almost surely, 2^{20510253400661} is an apocalyptic number.

It is an amenable number.

20510253400661 is a deficient number, since it is larger than the sum of its proper divisors (415312363).

20510253400661 is an equidigital number, since it uses as much as digits as its factorization.

20510253400661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415312362.

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 20510253400661 in words is "twenty trillion, five hundred ten billion, two hundred fifty-three million, four hundred thousand, six hundred sixty-one".