21057723026 has 4 divisors (see below), whose sum is σ = 31586584542. Its totient is φ = 10528861512.

The previous prime is 21057722999. The next prime is 21057723031. The reversal of 21057723026 is 62032775012.

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., 21025290001 + 32433025 = 145001^2 + 5695^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5264430755 + ... + 5264430758.

Almost surely, 2^21057723026 is an apocalyptic number.

21057723026 is a deficient number, since it is larger than the sum of its proper divisors (10528861516).

21057723026 is a wasteful number, since it uses less digits than its factorization.

21057723026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10528861515.

The product of its (nonzero) digits is 35280, while the sum is 35.

The spelling of 21057723026 in words is "twenty-one billion, fifty-seven million, seven hundred twenty-three thousand, twenty-six".