1525991 has 4 divisors (see below), whose sum is σ = 1567272. Its totient is φ = 1484712.

The previous prime is 1525987. The next prime is 1525999. The reversal of 1525991 is 1995251.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1995251 = 1063 ⋅1877.

It is a cyclic number.

It is not a de Polignac number, because 1525991 - 2² = 1525987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1525999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20585 + ... + 20658.

It is an arithmetic number, because the mean of its divisors is an integer number (391818).

2^1525991 is an apocalyptic number.

1525991 is a deficient number, since it is larger than the sum of its proper divisors (41281).

1525991 is an equidigital number, since it uses as much as digits as its factorization.

1525991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41280.

The product of its digits is 4050, while the sum is 32.

The square root of 1525991 is about 1235.3100825299. The cubic root of 1525991 is about 115.1288033826.

The spelling of 1525991 in words is "one million, five hundred twenty-five thousand, nine hundred ninety-one".