21521204151 has 8 divisors (see below), whose sum is σ = 28705238640. Its totient is φ = 14342319552.

The previous prime is 21521204147. The next prime is 21521204171. The reversal of 21521204151 is 15140212512.

It is a happy number.

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

It is not a de Polignac number, because 21521204151 - 2² = 21521204147 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521204171) 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, 1277710 + ... + 1294443.

It is an arithmetic number, because the mean of its divisors is an integer number (3588154830).

Almost surely, 2^21521204151 is an apocalyptic number.

21521204151 is a deficient number, since it is larger than the sum of its proper divisors (7184034489).

21521204151 is a wasteful number, since it uses less digits than its factorization.

21521204151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2574945.

The product of its (nonzero) digits is 800, while the sum is 24.

Adding to 21521204151 its reverse (15140212512), we get a palindrome (36661416663).

The spelling of 21521204151 in words is "twenty-one billion, five hundred twenty-one million, two hundred four thousand, one hundred fifty-one".