21951389523361 has 3 divisors (see below), whose sum is σ = 21951394208593. Its totient is φ = 21951384838130.

The previous prime is 21951389523341. The next prime is 21951389523377. The reversal of 21951389523361 is 16332598315912.

The square root of 21951389523361 is 4685231.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 21951389523361 - 2²¹ = 21951387426209 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21951389523296 and 21951389523305.

It is not an unprimeable number, because it can be changed into a prime (21951389523341) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2342616 + ... + 7027846.

Almost surely, 2^{21951389523361} is an apocalyptic number.

21951389523361 is the 4685231-st square number.

21951389523361 is the 2342616-th centered octagonal number.

It is an amenable number.

21951389523361 is a deficient number, since it is larger than the sum of its proper divisors (4685232).

21951389523361 is an frugal number, since it uses more digits than its factorization.

21951389523361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9370462 (or 4685231 counting only the distinct ones).

The product of its digits is 10497600, while the sum is 58.

The spelling of 21951389523361 in words is "twenty-one trillion, nine hundred fifty-one billion, three hundred eighty-nine million, five hundred twenty-three thousand, three hundred sixty-one".