21256797 has 16 divisors (see below), whose sum is σ = 29730240. Its totient is φ = 13491072.

The previous prime is 21256777. The next prime is 21256799. The reversal of 21256797 is 79765212.

It is not a de Polignac number, because 21256797 - 2⁶ = 21256733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256799) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4678 + ... + 8024.

It is an arithmetic number, because the mean of its divisors is an integer number (1858140).

Almost surely, 2^21256797 is an apocalyptic number.

It is an amenable number.

21256797 is a deficient number, since it is larger than the sum of its proper divisors (8473443).

21256797 is a wasteful number, since it uses less digits than its factorization.

21256797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3452.

The product of its digits is 52920, while the sum is 39.

The square root of 21256797 is about 4610.5094078637. The cubic root of 21256797 is about 277.0124414992.

The spelling of 21256797 in words is "twenty-one million, two hundred fifty-six thousand, seven hundred ninety-seven".