16512157021 has 4 divisors (see below), whose sum is σ = 16574941152. Its totient is φ = 16449372892.

The previous prime is 16512157019. The next prime is 16512157027. The reversal of 16512157021 is 12075121561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12075121561 = 27487 ⋅439303.

It is a cyclic number.

It is not a de Polignac number, because 16512157021 - 2¹ = 16512157019 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 (16512157027) 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, 31391671 + ... + 31392196.

It is an arithmetic number, because the mean of its divisors is an integer number (4143735288).

Almost surely, 2^16512157021 is an apocalyptic number.

It is an amenable number.

16512157021 is a deficient number, since it is larger than the sum of its proper divisors (62784131).

16512157021 is an equidigital number, since it uses as much as digits as its factorization.

16512157021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62784130.

The product of its (nonzero) digits is 4200, while the sum is 31.

Adding to 16512157021 its reverse (12075121561), we get a palindrome (28587278582).

The spelling of 16512157021 in words is "sixteen billion, five hundred twelve million, one hundred fifty-seven thousand, twenty-one".