21099137 has 4 divisors (see below), whose sum is σ = 21108480. Its totient is φ = 21089796.

The previous prime is 21099121. The next prime is 21099151. The reversal of 21099137 is 73199012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21099137 - 2⁴ = 21099121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21099157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1064 + ... + 6582.

It is an arithmetic number, because the mean of its divisors is an integer number (5277120).

Almost surely, 2^21099137 is an apocalyptic number.

It is an amenable number.

21099137 is a deficient number, since it is larger than the sum of its proper divisors (9343).

21099137 is an equidigital number, since it uses as much as digits as its factorization.

21099137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9342.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 21099137 is about 4593.3796925575. The cubic root of 21099137 is about 276.3258814362.

The spelling of 21099137 in words is "twenty-one million, ninety-nine thousand, one hundred thirty-seven".