21255722746 has 4 divisors (see below), whose sum is σ = 31883584122. Its totient is φ = 10627861372.

The previous prime is 21255722729. The next prime is 21255722821. The reversal of 21255722746 is 64722755212.

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., 16962197121 + 4293525625 = 130239^2 + 65525^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5313930685 + ... + 5313930688.

Almost surely, 2^21255722746 is an apocalyptic number.

21255722746 is a deficient number, since it is larger than the sum of its proper divisors (10627861376).

21255722746 is a wasteful number, since it uses less digits than its factorization.

21255722746 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10627861375.

The product of its digits is 470400, while the sum is 43.

The spelling of 21255722746 in words is "twenty-one billion, two hundred fifty-five million, seven hundred twenty-two thousand, seven hundred forty-six".