315890821 has 4 divisors (see below), whose sum is σ = 334472652. Its totient is φ = 297308992.

The previous prime is 315890819. The next prime is 315890831. The reversal of 315890821 is 128098513.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 196840900 + 119049921 = 14030^2 + 10911^2 .

It is a cyclic number.

It is not a de Polignac number, because 315890821 - 2¹ = 315890819 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 (315890831) 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, 9290890 + ... + 9290923.

It is an arithmetic number, because the mean of its divisors is an integer number (83618163).

Almost surely, 2^315890821 is an apocalyptic number.

It is an amenable number.

315890821 is a deficient number, since it is larger than the sum of its proper divisors (18581831).

315890821 is a wasteful number, since it uses less digits than its factorization.

315890821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18581830.

The product of its (nonzero) digits is 17280, while the sum is 37.

The square root of 315890821 is about 17773.3176700356. The cubic root of 315890821 is about 681.0500077201.

It can be divided in two parts, 315 and 890821, that added together give a square (891136 = 944²).

The spelling of 315890821 in words is "three hundred fifteen million, eight hundred ninety thousand, eight hundred twenty-one".