61636821381 has 6 divisors (see below), whose sum is σ = 89030964230. Its totient is φ = 41091214248.

The previous prime is 61636821373. The next prime is 61636821403. The reversal of 61636821381 is 18312863616.

61636821381 is a `hidden beast` number, since 6 + 1 + 636 + 8 + 2 + 1 + 3 + 8 + 1 = 666.

61636821381 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 60815998881 + 820822500 = 246609^2 + 28650^2 .

It is not a de Polignac number, because 61636821381 - 2³ = 61636821373 is a prime.

It is a super-2 number, since 2×61636821381² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61636821581) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3424267846 + ... + 3424267863.

Almost surely, 2^61636821381 is an apocalyptic number.

It is an amenable number.

61636821381 is a deficient number, since it is larger than the sum of its proper divisors (27394142849).

61636821381 is a wasteful number, since it uses less digits than its factorization.

61636821381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6848535715 (or 6848535712 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The spelling of 61636821381 in words is "sixty-one billion, six hundred thirty-six million, eight hundred twenty-one thousand, three hundred eighty-one".