749172821 has 4 divisors (see below), whose sum is σ = 749236032. Its totient is φ = 749109612.

The previous prime is 749172811. The next prime is 749172829. The reversal of 749172821 is 128271947.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 128271947 = 1933 ⋅66359.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-749172821 is a prime.

It is a super-2 number, since 2×749172821² = 1122519831450196082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (749172829) 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, 7901 + ... + 39506.

It is an arithmetic number, because the mean of its divisors is an integer number (187309008).

It is a Poulet number, since it divides 2^749172820-1.

Almost surely, 2^749172821 is an apocalyptic number.

749172821 is the 15803-rd octagonal number.

It is an amenable number.

749172821 is a deficient number, since it is larger than the sum of its proper divisors (63211).

749172821 is a wasteful number, since it uses less digits than its factorization.

749172821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63210.

The product of its digits is 56448, while the sum is 41.

The square root of 749172821 is about 27371.0215556526. The cubic root of 749172821 is about 908.2261548783.

The spelling of 749172821 in words is "seven hundred forty-nine million, one hundred seventy-two thousand, eight hundred twenty-one".