1221921937 has 16 divisors (see below), whose sum is σ = 1318798800. Its totient is φ = 1128038400.

The previous prime is 1221921923. The next prime is 1221921949. The reversal of 1221921937 is 7391291221.

It is a Cunningham number, because it is equal to 34956²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 105760656 + 1116161281 = 10284^2 + 33409^2 .

It is not a de Polignac number, because 1221921937 - 2¹⁹ = 1221397649 is a prime.

It is a super-3 number, since 3×1221921937³ (a number of 28 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221921896 and 1221921905.

It is not an unprimeable number, because it can be changed into a prime (1221921907) 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, 183889 + ... + 190417.

It is an arithmetic number, because the mean of its divisors is an integer number (82424925).

Almost surely, 2^1221921937 is an apocalyptic number.

1221921937 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1221921937 is a deficient number, since it is larger than the sum of its proper divisors (96876863).

1221921937 is a wasteful number, since it uses less digits than its factorization.

1221921937 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6756.

The product of its digits is 13608, while the sum is 37.

The square root of 1221921937 is about 34956.0000143037. Note that the first 4 decimals coincide. The cubic root of 1221921937 is about 1069.0905414486.

The spelling of 1221921937 in words is "one billion, two hundred twenty-one million, nine hundred twenty-one thousand, nine hundred thirty-seven".