16121201556 has 24 divisors (see below), whose sum is σ = 37661535520. Its totient is φ = 5367248352.

The previous prime is 16121201531. The next prime is 16121201563. The reversal of 16121201556 is 65510212161.

It is a super-2 number, since 2×16121201556² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 800326 + ... + 820221.

Almost surely, 2^16121201556 is an apocalyptic number.

It is an amenable number.

16121201556 is an abundant number, since it is smaller than the sum of its proper divisors (21540333964).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16121201556 is a wasteful number, since it uses less digits than its factorization.

16121201556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1621383 (or 1621381 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 30.

The spelling of 16121201556 in words is "sixteen billion, one hundred twenty-one million, two hundred one thousand, five hundred fifty-six".