20891306 has 4 divisors (see below), whose sum is σ = 31336962. Its totient is φ = 10445652.

The previous prime is 20891293. The next prime is 20891333. The reversal of 20891306 is 60319802.

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., 19439281 + 1452025 = 4409^2 + 1205^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5222825 + ... + 5222828.

Almost surely, 2^20891306 is an apocalyptic number.

20891306 is a deficient number, since it is larger than the sum of its proper divisors (10445656).

20891306 is a wasteful number, since it uses less digits than its factorization.

20891306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10445655.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 20891306 is about 4570.7008215371. The cubic root of 20891306 is about 275.4155964029.

The spelling of 20891306 in words is "twenty million, eight hundred ninety-one thousand, three hundred six".