721641405 has 16 divisors (see below), whose sum is σ = 1191873024. Its totient is φ = 372459840.

The previous prime is 721641397. The next prime is 721641409. The reversal of 721641405 is 504146127.

It is not a de Polignac number, because 721641405 - 2³ = 721641397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721641409) 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, 775494 + ... + 776423.

It is an arithmetic number, because the mean of its divisors is an integer number (74492064).

Almost surely, 2^721641405 is an apocalyptic number.

It is an amenable number.

721641405 is a deficient number, since it is larger than the sum of its proper divisors (470231619).

721641405 is a wasteful number, since it uses less digits than its factorization.

721641405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1551956.

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 721641405 is about 26863.3840943393. The cubic root of 721641405 is about 896.9615250043.

The spelling of 721641405 in words is "seven hundred twenty-one million, six hundred forty-one thousand, four hundred five".