21030137 has 4 divisors (see below), whose sum is σ = 21386640. Its totient is φ = 20673636.

The previous prime is 21030127. The next prime is 21030181. The reversal of 21030137 is 73103012.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21030137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21030127) 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, 178163 + ... + 178280.

It is an arithmetic number, because the mean of its divisors is an integer number (5346660).

Almost surely, 2^21030137 is an apocalyptic number.

It is an amenable number.

21030137 is a deficient number, since it is larger than the sum of its proper divisors (356503).

21030137 is an equidigital number, since it uses as much as digits as its factorization.

21030137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356502.

The product of its (nonzero) digits is 126, while the sum is 17.

The square root of 21030137 is about 4585.8627323547. The cubic root of 21030137 is about 276.0243318533.

Adding to 21030137 its reverse (73103012), we get a palindrome (94133149).

The spelling of 21030137 in words is "twenty-one million, thirty thousand, one hundred thirty-seven".