1401645255921 has 9 divisors (see below), whose sum is σ = 2024603833291. Its totient is φ = 934427802792.

The previous prime is 1401645255893. The next prime is 1401645255931. The reversal of 1401645255921 is 1295525461041.

The square root of 1401645255921 is 1183911.

It is a perfect power (a square), and thus also a powerful number.

1401645255921 is a `hidden beast` number, since 1 + 4 + 0 + 1 + 6 + 4 + 52 + 5 + 592 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1115167680225 + 286477575696 = 1056015^2 + 535236^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1401645255921 - 2²⁵ = 1401611701489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1401645255931) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3354415 + ... + 3749051.

Almost surely, 2^{1401645255921} is an apocalyptic number.

1401645255921 is the 1183911-st square number.

1401645255921 is the 591956-th centered octagonal number.

It is an amenable number.

1401645255921 is a deficient number, since it is larger than the sum of its proper divisors (622958577370).

1401645255921 is an frugal number, since it uses more digits than its factorization.

1401645255921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 789280 (or 394640 counting only the distinct ones).

The product of its (nonzero) digits is 432000, while the sum is 45.

The spelling of 1401645255921 in words is "one trillion, four hundred one billion, six hundred forty-five million, two hundred fifty-five thousand, nine hundred twenty-one".