21131045 has 8 divisors (see below), whose sum is σ = 27307896. Its totient is φ = 15604416.

The previous prime is 21131041. The next prime is 21131069. The reversal of 21131045 is 54013112.

It can be written as a sum of positive squares in 4 ways, for example, as 863041 + 20268004 = 929^2 + 4502^2 .

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 21131045 - 2² = 21131041 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 (21131041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 162482 + ... + 162611.

It is an arithmetic number, because the mean of its divisors is an integer number (3413487).

Almost surely, 2^21131045 is an apocalyptic number.

It is an amenable number.

21131045 is a deficient number, since it is larger than the sum of its proper divisors (6176851).

21131045 is a wasteful number, since it uses less digits than its factorization.

21131045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325111.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21131045 is about 4596.8516399814. The cubic root of 21131045 is about 276.4651061722.

Adding to 21131045 its reverse (54013112), we get a palindrome (75144157).

The spelling of 21131045 in words is "twenty-one million, one hundred thirty-one thousand, forty-five".