77521428 has 48 divisors (see below), whose sum is σ = 212808960. Its totient is φ = 24319872.

The previous prime is 77521427. The next prime is 77521429. The reversal of 77521428 is 82412577.

It is an interprime number because it is at equal distance from previous prime (77521427) and next prime (77521429).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 77521392 and 77521401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77521427) 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, 19276 + ... + 22947.

It is an arithmetic number, because the mean of its divisors is an integer number (4433520).

Almost surely, 2^77521428 is an apocalyptic number.

It is an amenable number.

77521428 is an abundant number, since it is smaller than the sum of its proper divisors (135287532).

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

77521428 is a wasteful number, since it uses less digits than its factorization.

77521428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42253 (or 42245 counting only the distinct ones).

The product of its digits is 31360, while the sum is 36.

The square root of 77521428 is about 8804.6253753354. The cubic root of 77521428 is about 426.3902395137.

It can be divided in two parts, 7752 and 1428, that added together give a triangular number (9180 = T₁₃₅).

The spelling of 77521428 in words is "seventy-seven million, five hundred twenty-one thousand, four hundred twenty-eight".