90721399 has 4 divisors (see below), whose sum is σ = 91278136. Its totient is φ = 90164664.

The previous prime is 90721391. The next prime is 90721429. The reversal of 90721399 is 99312709.

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

It is a cyclic number.

It is not a de Polignac number, because 90721399 - 2³ = 90721391 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 (90721391) 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, 278124 + ... + 278449.

It is an arithmetic number, because the mean of its divisors is an integer number (22819534).

Almost surely, 2^90721399 is an apocalyptic number.

90721399 is a deficient number, since it is larger than the sum of its proper divisors (556737).

90721399 is a wasteful number, since it uses less digits than its factorization.

90721399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 556736.

The product of its (nonzero) digits is 30618, while the sum is 40.

The square root of 90721399 is about 9524.7781601463. The cubic root of 90721399 is about 449.3346529506.

The spelling of 90721399 in words is "ninety million, seven hundred twenty-one thousand, three hundred ninety-nine".