77121531 has 8 divisors (see below), whose sum is σ = 114254160. Its totient is φ = 51414336.

The previous prime is 77121491. The next prime is 77121557. The reversal of 77121531 is 13512177.

It is a happy number.

77121531 is a `hidden beast` number, since 7 + 7 + 121 + 531 = 666.

It is not a de Polignac number, because 77121531 - 2⁶ = 77121467 is a prime.

It is a super-2 number, since 2×77121531² = 11895461087567922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 2856353 = 77121531 / (7 + 7 + 1 + 2 + 1 + 5 + 3 + 1).

It is a junction number, because it is equal to n+sod(n) for n = 77121495 and 77121504.

It is not an unprimeable number, because it can be changed into a prime (77121581) 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, 1428150 + ... + 1428203.

It is an arithmetic number, because the mean of its divisors is an integer number (14281770).

Almost surely, 2^77121531 is an apocalyptic number.

77121531 is a deficient number, since it is larger than the sum of its proper divisors (37132629).

77121531 is a wasteful number, since it uses less digits than its factorization.

77121531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2856362 (or 2856356 counting only the distinct ones).

The product of its digits is 1470, while the sum is 27.

The square root of 77121531 is about 8781.8865285313. The cubic root of 77121531 is about 425.6557921793.

The spelling of 77121531 in words is "seventy-seven million, one hundred twenty-one thousand, five hundred thirty-one".