21004151531 has 8 divisors (see below), whose sum is σ = 22918931184. Its totient is φ = 19090257120.

The previous prime is 21004151507. The next prime is 21004151537. The reversal of 21004151531 is 13515140012.

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

It is a de Polignac number, because none of the positive numbers 2^k-21004151531 is a prime.

It is a super-2 number, since 2×21004151531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21004151497 and 21004151506.

It is not an unprimeable number, because it can be changed into a prime (21004151537) 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, 171200 + ... + 267053.

It is an arithmetic number, because the mean of its divisors is an integer number (2864866398).

Almost surely, 2^21004151531 is an apocalyptic number.

21004151531 is a deficient number, since it is larger than the sum of its proper divisors (1914779653).

21004151531 is a wasteful number, since it uses less digits than its factorization.

21004151531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442621.

The product of its (nonzero) digits is 600, while the sum is 23.

Adding to 21004151531 its reverse (13515140012), we get a palindrome (34519291543).

The spelling of 21004151531 in words is "twenty-one billion, four million, one hundred fifty-one thousand, five hundred thirty-one".