2145769921 has 6 divisors (see below), whose sum is σ = 2264649522. Its totient is φ = 2032834320.

The previous prime is 2145769919. The next prime is 2145769931. The reversal of 2145769921 is 1299675412.

It can be written as a sum of positive squares in only one way, i.e., 2070705025 + 75064896 = 45505^2 + 8664^2 .

It is not a de Polignac number, because 2145769921 - 2¹ = 2145769919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2145769931) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2971620 + ... + 2972341.

It is an arithmetic number, because the mean of its divisors is an integer number (377441587).

Almost surely, 2^2145769921 is an apocalyptic number.

It is an amenable number.

2145769921 is a deficient number, since it is larger than the sum of its proper divisors (118879601).

2145769921 is an equidigital number, since it uses as much as digits as its factorization.

2145769921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5943999 (or 5943980 counting only the distinct ones).

The product of its digits is 272160, while the sum is 46.

The square root of 2145769921 is about 46322.4559042372. The cubic root of 2145769921 is about 1289.8158744075.

It can be divided in two parts, 21457 and 69921, that added together give a triangular number (91378 = T₄₂₇).

The spelling of 2145769921 in words is "two billion, one hundred forty-five million, seven hundred sixty-nine thousand, nine hundred twenty-one".