21365025770261 has 4 divisors (see below), whose sum is σ = 21365038923072. Its totient is φ = 21365012617452.

The previous prime is 21365025770233. The next prime is 21365025770267. The reversal of 21365025770261 is 16207752056312.

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 a de Polignac number, because none of the positive numbers 2^k-21365025770261 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21365025770267) 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, 3728861 + ... + 7525586.

It is an arithmetic number, because the mean of its divisors is an integer number (5341259730768).

Almost surely, 2^{21365025770261} is an apocalyptic number.

It is an amenable number.

21365025770261 is a deficient number, since it is larger than the sum of its proper divisors (13152811).

21365025770261 is a wasteful number, since it uses less digits than its factorization.

21365025770261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13152810.

The product of its (nonzero) digits is 1058400, while the sum is 47.

The spelling of 21365025770261 in words is "twenty-one trillion, three hundred sixty-five billion, twenty-five million, seven hundred seventy thousand, two hundred sixty-one".