21099757 has 16 divisors (see below), whose sum is σ = 25067520. Its totient is φ = 17384688.

The previous prime is 21099751. The next prime is 21099761. The reversal of 21099757 is 75799012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21099757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099751) 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, 18868 + ... + 19954.

It is an arithmetic number, because the mean of its divisors is an integer number (1566720).

Almost surely, 2^21099757 is an apocalyptic number.

It is an amenable number.

21099757 is a deficient number, since it is larger than the sum of its proper divisors (3967763).

21099757 is a wasteful number, since it uses less digits than its factorization.

21099757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1200.

The product of its (nonzero) digits is 39690, while the sum is 40.

The square root of 21099757 is about 4593.4471804953. The cubic root of 21099757 is about 276.3285880298.

The spelling of 21099757 in words is "twenty-one million, ninety-nine thousand, seven hundred fifty-seven".