921721851 has 12 divisors (see below), whose sum is σ = 1332258928. Its totient is φ = 614073744.

The previous prime is 921721817. The next prime is 921721883. The reversal of 921721851 is 158127129.

It is a happy number.

It is not a de Polignac number, because 921721851 - 2¹¹ = 921719803 is a prime.

It is a super-2 number, since 2×921721851² = 1699142341221732402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (921721811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19300 + ... + 47073.

Almost surely, 2^921721851 is an apocalyptic number.

921721851 is a deficient number, since it is larger than the sum of its proper divisors (410537077).

921721851 is a wasteful number, since it uses less digits than its factorization.

921721851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67922 (or 67919 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The square root of 921721851 is about 30359.8723811547. The cubic root of 921721851 is about 973.1952064292.

The spelling of 921721851 in words is "nine hundred twenty-one million, seven hundred twenty-one thousand, eight hundred fifty-one".