1276621721 has 2 divisors, whose sum is σ = 1276621722. Its totient is φ = 1276621720.

The previous prime is 1276621663. The next prime is 1276621727. The reversal of 1276621721 is 1271266721.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1015314496 + 261307225 = 31864^2 + 16165^2 .

It is a cyclic number.

It is not a de Polignac number, because 1276621721 - 2²² = 1272427417 is a prime.

It is not a weakly prime, because it can be changed into another prime (1276621727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 638310860 + 638310861.

It is an arithmetic number, because the mean of its divisors is an integer number (638310861).

Almost surely, 2^1276621721 is an apocalyptic number.

It is an amenable number.

1276621721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1276621721 is an equidigital number, since it uses as much as digits as its factorization.

1276621721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 35.

The square root of 1276621721 is about 35729.8435624899. The cubic root of 1276621721 is about 1084.8109904573.

The spelling of 1276621721 in words is "one billion, two hundred seventy-six million, six hundred twenty-one thousand, seven hundred twenty-one".