21012157 has 8 divisors (see below), whose sum is σ = 22161600. Its totient is φ = 19867104.

The previous prime is 21012151. The next prime is 21012161. The reversal of 21012157 is 75121012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21012157 - 2¹⁵ = 20979389 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14688 + ... + 16054.

It is an arithmetic number, because the mean of its divisors is an integer number (2770200).

Almost surely, 2^21012157 is an apocalyptic number.

It is an amenable number.

21012157 is a deficient number, since it is larger than the sum of its proper divisors (1149443).

21012157 is a wasteful number, since it uses less digits than its factorization.

21012157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2195.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 21012157 is about 4583.9019404869. The cubic root of 21012157 is about 275.9456458462.

Adding to 21012157 its reverse (75121012), we get a palindrome (96133169).

The spelling of 21012157 in words is "twenty-one million, twelve thousand, one hundred fifty-seven".