21154013 has 8 divisors (see below), whose sum is σ = 21575736. Its totient is φ = 20736000.

The previous prime is 21153971. The next prime is 21154019. The reversal of 21154013 is 31045112.

It can be written as a sum of positive squares in 4 ways, for example, as 4072324 + 17081689 = 2018^2 + 4133^2 .

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 21154013 - 2⁸ = 21153757 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21153982 and 21154000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154019) 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, 12413 + ... + 14013.

It is an arithmetic number, because the mean of its divisors is an integer number (2696967).

Almost surely, 2^21154013 is an apocalyptic number.

It is an amenable number.

21154013 is a deficient number, since it is larger than the sum of its proper divisors (421723).

21154013 is a wasteful number, since it uses less digits than its factorization.

21154013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1855.

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

The square root of 21154013 is about 4599.3491930924. The cubic root of 21154013 is about 276.5652361205.

Adding to 21154013 its reverse (31045112), we get a palindrome (52199125).

It can be divided in two parts, 2 and 1154013, that multiplied together give a triangular number (2308026 = T₂₁₄₈).

The spelling of 21154013 in words is "twenty-one million, one hundred fifty-four thousand, thirteen".