21769257 has 16 divisors (see below), whose sum is σ = 29730240. Its totient is φ = 14164992.

The previous prime is 21769249. The next prime is 21769261. The reversal of 21769257 is 75296712.

It is not a de Polignac number, because 21769257 - 2³ = 21769249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21769057) 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, 22969 + ... + 23897.

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

Almost surely, 2^21769257 is an apocalyptic number.

It is an amenable number.

21769257 is a deficient number, since it is larger than the sum of its proper divisors (7960983).

21769257 is a wasteful number, since it uses less digits than its factorization.

21769257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1112.

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

The square root of 21769257 is about 4665.7536368737. The cubic root of 21769257 is about 279.2208654354.

The spelling of 21769257 in words is "twenty-one million, seven hundred sixty-nine thousand, two hundred fifty-seven".