21275757 has 16 divisors (see below), whose sum is σ = 31752000. Its totient is φ = 14079312.

The previous prime is 21275747. The next prime is 21275809. The reversal of 21275757 is 75757212.

It is not a de Polignac number, because 21275757 - 2⁶ = 21275693 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21275707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 919 + ... + 6587.

It is an arithmetic number, because the mean of its divisors is an integer number (1984500).

Almost surely, 2^21275757 is an apocalyptic number.

21275757 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21275757 is a deficient number, since it is larger than the sum of its proper divisors (10476243).

21275757 is a wasteful number, since it uses less digits than its factorization.

21275757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5817 (or 5811 counting only the distinct ones).

The product of its digits is 34300, while the sum is 36.

The square root of 21275757 is about 4612.5651214915. The cubic root of 21275757 is about 277.0947774395.

The spelling of 21275757 in words is "twenty-one million, two hundred seventy-five thousand, seven hundred fifty-seven".