21255400366666 has 4 divisors (see below), whose sum is σ = 31883100550002. Its totient is φ = 10627700183332.

The previous prime is 21255400366643. The next prime is 21255400366709. The reversal of 21255400366666 is 66666300455212.

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

It can be written as a sum of positive squares in only one way, i.e., 13390264251441 + 7865136115225 = 3659271^2 + 2804485^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5313850091665 + ... + 5313850091668.

Almost surely, 2^{21255400366666} is an apocalyptic number.

21255400366666 is a deficient number, since it is larger than the sum of its proper divisors (10627700183336).

21255400366666 is a wasteful number, since it uses less digits than its factorization.

21255400366666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10627700183335.

The product of its (nonzero) digits is 9331200, while the sum is 52.

The spelling of 21255400366666 in words is "twenty-one trillion, two hundred fifty-five billion, four hundred million, three hundred sixty-six thousand, six hundred sixty-six".