21250405102655 has 4 divisors (see below), whose sum is σ = 25500486123192. Its totient is φ = 17000324082120.

The previous prime is 21250405102643. The next prime is 21250405102657. The reversal of 21250405102655 is 55620150405212.

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

It is not a de Polignac number, because 21250405102655 - 2²² = 21250400908351 is a prime.

It is a super-2 number, since 2×21250405102655² (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 (21250405102657) 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, 2125040510261 + ... + 2125040510270.

It is an arithmetic number, because the mean of its divisors is an integer number (6375121530798).

Almost surely, 2^{21250405102655} is an apocalyptic number.

21250405102655 is a deficient number, since it is larger than the sum of its proper divisors (4250081020537).

21250405102655 is an equidigital number, since it uses as much as digits as its factorization.

21250405102655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4250081020536.

The product of its (nonzero) digits is 120000, while the sum is 38.

Adding to 21250405102655 its reverse (55620150405212), we get a palindrome (76870555507867).

The spelling of 21250405102655 in words is "twenty-one trillion, two hundred fifty billion, four hundred five million, one hundred two thousand, six hundred fifty-five".