21120151 has 4 divisors (see below), whose sum is σ = 22744792. Its totient is φ = 19495512.

The previous prime is 21120139. The next prime is 21120163. The reversal of 21120151 is 15102112.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21120139) and next prime (21120163).

It is a cyclic number.

It is not a de Polignac number, because 21120151 - 2⁵ = 21120119 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 1624627 = 21120151 / (2 + 1 + 1 + 2 + 0 + 1 + 5 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120131) 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, 812301 + ... + 812326.

It is an arithmetic number, because the mean of its divisors is an integer number (5686198).

Almost surely, 2^21120151 is an apocalyptic number.

21120151 is a deficient number, since it is larger than the sum of its proper divisors (1624641).

21120151 is a wasteful number, since it uses less digits than its factorization.

21120151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1624640.

The product of its (nonzero) digits is 20, while the sum is 13.

The square root of 21120151 is about 4595.6665457798. Note that the first 3 decimals coincide. The cubic root of 21120151 is about 276.4175879577.

Adding to 21120151 its reverse (15102112), we get a palindrome (36222263).

The spelling of 21120151 in words is "twenty-one million, one hundred twenty thousand, one hundred fifty-one".