55151721561 has 16 divisors (see below), whose sum is σ = 73892590848. Its totient is φ = 36589766400.

The previous prime is 55151721557. The next prime is 55151721577. The reversal of 55151721561 is 16512715155.

It is a happy number.

It is not a de Polignac number, because 55151721561 - 2² = 55151721557 is a prime.

It is a super-2 number, since 2×55151721561² (a number of 22 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (55151721511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 459601 + ... + 567041.

It is an arithmetic number, because the mean of its divisors is an integer number (4618286928).

Almost surely, 2^55151721561 is an apocalyptic number.

It is an amenable number.

55151721561 is a deficient number, since it is larger than the sum of its proper divisors (18740869287).

55151721561 is a wasteful number, since it uses less digits than its factorization.

55151721561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108272.

The product of its digits is 52500, while the sum is 39.

The spelling of 55151721561 in words is "fifty-five billion, one hundred fifty-one million, seven hundred twenty-one thousand, five hundred sixty-one".